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Carboxy-terminal processing proteases (CTPs) occur in all three domains of life. In bacteria, some of them have been associated with virulence. However, the precise roles of bacterial CTPs are poorly understood, and few direct proteolytic substrates have been identified. One bacterial CTP is the CtpA protease of Pseudomonas aeruginosa , which is required for type III secretion system (T3SS) function and for virulence in a mouse model of acute pneumonia. Here, we have investigated the function of CtpA in P. aeruginosa and identified some of the proteins it cleaves. We discovered that CtpA forms a complex with a previously uncharacterized protein, which we have named LbcA ( l ipoprotein b inding partner of C tpA). LbcA is required for CtpA activity in vivo and promotes its activity in vitro . We have also identified four proteolytic substrates of CtpA, all of which are uncharacterized proteins predicted to cleave the peptide cross-links within peptidoglycan. Consistent with this, a ctpA null mutant was found to have fewer peptidoglycan cross-links than the wild type and grew slowly in salt-free medium. Intriguingly, the accumulation of just one of the CtpA substrates was required for some Δ ctpA mutant phenotypes, including the defective T3SS. We propose that LbcA-CtpA is a proteolytic complex in the P. aeruginosa cell envelope, which controls the activity of several peptidoglycan cross-link hydrolases by degrading them. Furthermore, based on these and other findings, we suggest that many bacterial CTPs might be similarly controlled by partner proteins as part of a widespread mechanism to control peptidoglycan hydrolase activity. IMPORTANCE Bacterial carboxy-terminal processing proteases (CTPs) are widely conserved and have been associated with the virulence of several species. However, their roles are poorly understood, and few direct substrates have been identified in any species. Pseudomonas aeruginosa is an important human pathogen in which one CTP, known as CtpA, is required for type III secretion system function and for virulence. This work provides an important advance by showing that CtpA works with a previously uncharacterized binding partner to degrade four substrates. These substrates are all predicted to hydrolyze peptidoglycan cross-links, suggesting that the CtpA complex is an important control mechanism for peptidoglycan hydrolysis. This is likely to emerge as a widespread mechanism used by diverse bacteria to control some of their peptidoglycan hydrolases. This is significant, given the links between CTPs and virulence in several pathogens and the importance of peptidoglycan remodeling to almost all bacterial cells. Bacterial carboxy-terminal processing proteases (CTPs) are widely conserved and have been associated with the virulence of several species. However, their roles are poorly understood, and few direct substrates have been identified in any species. Pseudomonas aeruginosa is an important human pathogen in which one CTP, known as CtpA, is required for type III secretion system function and for virulence. This work provides an important advance by showing that CtpA works with a previously uncharacterized binding partner to degrade four substrates. These substrates are all predicted to hydrolyze peptidoglycan cross-links, suggesting that the CtpA complex is an important control mechanism for peptidoglycan hydrolysis. This is likely to emerge as a widespread mechanism used by diverse bacteria to control some of their peptidoglycan hydrolases. This is significant, given the links between CTPs and virulence in several pathogens and the importance of peptidoglycan remodeling to almost all bacterial cells.

The bacterial phage shock protein system (Psp) is a conserved extracytoplasmic stress response that is essential for the virulence of some pathogens, including Yersinia enterocolitica . It is induced by events that can compromise inner membrane (IM) integrity, including the mislocalization of outer membrane pore-forming proteins called secretins. In the absence of the Psp system, secretin mislocalization permeabilizes the IM and causes rapid cell death. The Psp proteins PspB and PspC form an integral IM complex with two independent roles. First, the PspBC complex is required to activate the Psp response in response to some inducing triggers, including a mislocalized secretin. Second, PspBC are sufficient to counteract mislocalized secretin toxicity. Remarkably, secretin mislocalization into the IM induces psp gene expression without significantly affecting the expression of any other genes. Furthermore, psp null strains are killed by mislocalized secretins, whereas no other null mutants have been found to share this specific secretin sensitivity. This suggests an exquisitely specific relationship between secretins and the Psp system, but there has been no mechanism described to explain this. In this study, we addressed this deficiency by using a coimmunoprecipitation approach to show that the Psp proteins form a specific complex with mislocalized secretins in the Y. enterocolitica IM. Importantly, analysis of different secretin mutant proteins also revealed that this interaction is absolutely dependent on a secretin adopting a multimeric state. Therefore, the Psp system has evolved with the ability to detect and detoxify dangerous secretin multimers while ignoring the presence of innocuous monomers. IMPORTANCE The phage shock protein (Psp) response has been linked to important phenotypes in diverse bacteria, including those related to antibiotic resistance, biofilm formation, and virulence. This has generated widespread interest in understanding various aspects of its function. Outer membrane secretin proteins are essential components of export systems required for the virulence of many bacterial pathogens. However, secretins can mislocalize into the inner membrane, and this induces the Psp response in a highly specific manner and kills Psp-defective strains with similar specificity. There has been no mechanism described to explain this exquisitely specific relationship between secretins and the Psp system. Therefore, this study provides a critical advance by discovering that Psp effector proteins form a complex with secretins in the Yersinia enterocolitica inner membrane. Remarkably, this interaction is absolutely dependent on a secretin adopting its multimeric state. Therefore, the Psp system detects and detoxifies dangerous secretin multimers, while ignoring the presence of innocuous secretin monomers. The phage shock protein (Psp) response has been linked to important phenotypes in diverse bacteria, including those related to antibiotic resistance, biofilm formation, and virulence. This has generated widespread interest in understanding various aspects of its function. Outer membrane secretin proteins are essential components of export systems required for the virulence of many bacterial pathogens. However, secretins can mislocalize into the inner membrane, and this induces the Psp response in a highly specific manner and kills Psp-defective strains with similar specificity. There has been no mechanism described to explain this exquisitely specific relationship between secretins and the Psp system. Therefore, this study provides a critical advance by discovering that Psp effector proteins form a complex with secretins in the Yersinia enterocolitica inner membrane. Remarkably, this interaction is absolutely dependent on a secretin adopting its multimeric state. Therefore, the Psp system detects and detoxifies dangerous secretin multimers, while ignoring the presence of innocuous secretin monomers.

Free Space Optical (FSO) communication systems are gaining popularity due to its tremendous speed, advanced capacity, cost effectiveness, secure and easy to deploy wireless networks. This technology has proven an effective choice for last mile applications and hard to reach areas where deployment of optical fibre links is not feasible. But FSO link is highly weather dependent and as signal passes through the atmospheric channel, the main impairments are the atmospheric turbulence, which induce fading and deteriorate the system performance. Delhi has a great potential for FSO communication because of its clear skies. Since there is no analysis for weather condition found in Delhi, this work provides analysis of typical Delhi weather condition ranging from heavy to light rain, fog and clear sky. The performance of FSO link is analysed in terms of attenuation and link length margin under different weather condition. The results are concluded to identify which atmospheric condition influences more on FSO link performance.

As single laser beam cannot deal with the effect of turbulent atmospheric channels in free space optic (FSO) system, so we have proposed a novel hybrid WDM/multiple-beam system which can reduce the effects of tropical rain weather condition and provide a significant enhancement in the link range, scalability and received optical power. The result indicates that the SNR and FSO link ranges are improved by 20 dB and 3 km, respectively, by using the proposed technique in contrast to previous techniques.

Bacteria sense and respond to environmental cues to control important developmental processes. Decoding the language of chemical signaling in bacteria and the mechanisms by which these signals control coordinated behavior impacts our understanding of the role of bacteria in human health, the environment, and industrial processes. Bacteria exist in communities and often perform coordinated activities such as production and secretion of extracellular enzymes, luminescence, biofilm formation, and virulence. Vibrio cholerae, the causative agent of the diarrheal disease Cholera provides an excellent model system to study the effect of environmental signals on bacterial phenotypes. In V. cholerae, c-di-GMP affects transcriptome changes regulating many important phenotypes, such as biofilms and motility. I have identified two c-di-GMP binding transcription factors, VpsR and FlrA, involved in biofilm and motility, respectively. Currently, ten c-di-GMP binding transcription factors are known in bacteria, three of which are from V. cholerae. Three c-di-GMP binding transcription factors; FleQ, FlrA and VpsR belong to the NtrC-like enhancer binding protein family (EBPs). EBPs consist of an N-terminal receiver domain, central AAA+ domain (ATPase associated with diverse activities), and a C-terminal helix-turn-helix DNA binding domain. AAA+ domains are involved in ATP hydrolysis which drives open complex formation initiating transcription. The AAA+ domains are widespread in bacteria and are found in both transcription factors and other cellular machinery. The transcription factor VpsR binds c-di-GMP to induce biofilm gene expression. Alternatively, binding of c-di-GMP to FlrA, the master regulator of flagellar biosynthesis in V. cholerae, abrogates its ability to initiate downstream flagellar gene expression leading to a repression in motility. VpsR and FlrA exhibit the most homology in the AAA+ domain. I have discovered that the AAA+ domain of FlrA is important for interacting with c-di-GMP and demonstrated that two arginine residues are important for this binding. I have also isolated constitutively active mutants of VpsR which can be utilized to study the mechanism how c-di-GMP controls VpsR activity. Lastly, I have shown that other c-di-GMP regulated genes in V. cholerae are not regulated by known c-di-GMP binding transcription factors, suggesting that other unidentified machinery are involved in c-di-GMP signaling.

The need for high speed communications networks has led the research communities and industry to develop reliable, scalable transatlantic and transpacific fiber-optic communication links. In this paper the optimum Golomb ruler based 2D OCDMA codes has been demonstrated. An OCDMA system based on the discussed 2D codes is designed and simulated on Optisystem. The encoder and decoder structure of OCDMA system have been designed using filter and time delays. Further the performance is analysed for various parameter such as bit rate, number of users, BER (Bit Error Rate), quality factor, eye diagram and signal diagram. The system is analyzed for up to 18 users at 1 Gbps and 1.25 Gbps bit rate.

Free Space Optical (FSO) communication offers a promising technology for future high speed networks by providing huge transmission bandwidth, light weight, small size, low cost, low power and license free deployment as compared to the present radio frequency systems. Since in FSO communication, the atmosphere is used as a channel, atmospheric turbulence effects cause fading and misalignment of signal at the receiver and deteriorate the Bit Error Rate (BER) performance. This paper is focused on analyzing the FSO communication system performance in Delhi by modeling FSO communication system using basic Wavelength Division Multiplexing (WDM) technique with optimizing several system parameters in different turbulent environments such as fog and rain. Performance is analyzed in terms of Signal-to-Noise Ratio (SNR), received optical power and BER for different meteorological effects at data rate of 2.5 Gbps, 5 Gbps and 15 Gbps. From the results, it is concluded that the quality of received signal can be improved with priority-based optimization of parameters that increases link range up to 115 km in clear weather condition at 15 Gbps.

Carboxy-terminal processing proteases (CTPs) occur in all three domains of life. In bacteria some of them have been associated with virulence. However, the precise roles of bacterial CTPs are poorly understood and few direct proteolytic substrates have been identified. One bacterial CTP is the CtpA protease of Pseudomonas aeruginosa, which is required for type III secretion system function, and for virulence in a mouse model of acute pneumonia. Here, we have investigated the function of CtpA in P. aeruginosa and identified some of the proteins it cleaves. We discovered that CtpA forms a complex with a previously uncharacterized protein, which we have named LbcA (lipoprotein binding partner of CtpA). LbcA is required for CtpA activity in vivo and promotes its activity in vitro. We have also identified four proteolytic substrates of CtpA, all of which are uncharacterized proteins predicted to cleave the peptide cross-links within peptidoglycan. Consistent with this, a ctpA null mutant was found to have fewer peptidoglycan cross-links than the wild type and grew slowly in salt-free medium. Intriguingly, the accumulation of just one of the CtpA substrates was required for some ctpA mutant phenotypes, including the defective T3SS. We propose that LbcA-CtpA is a proteolytic complex in the P. aeruginosa cell envelope, which controls the activity of several peptidoglycan cross-link hydrolases by degrading them. Furthermore, based on these and other findings we suggest that many bacterial CTPs might be similarly controlled by partner proteins as part of a widespread mechanism to control peptidoglycan hydrolase activity.

Immune responses at the respiratory mucosal interface are critical to prevent respiratory infections but it is unclear to what extent antigen specific mucosal secretory IgA (SIgA) antibodies are induced by mRNA vaccination in humans. Here we analyze paired serum and saliva samples from patients with and without prior coronavirus disease 2019 (COVID-19) at multiple time points pre and post severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) mRNA vaccination. Our results suggest mucosal SIgA responses induced by mRNA vaccination are impacted by pre-existing immunity. Indeed, vaccination induced a minimal mucosal SIgA response in individuals without pre-exposure to SARS-CoV-2 while SIgA induction after vaccination was more efficient in patients with a history of COVID-19. Prior exposure to infectious agents can impact the vaccination induced immune response. Here the authors show prior SARS-CoV-2 infection results in more efficient induction of mucosal SARS-CoV-2 secretory IgA antibody following mRNA vaccination.

The integration of multiple modalities in medical imaging allows a thorough representation of structural and functional details, resulting in improved diagnosis and treatment. Deep learning methods outperform conventional methods by automating the extraction of pertinent features and fusing them while preserving both structural and textural integrity. Existing methods lack the ability to capture complex global structures, small-scale textural features, and long-range dependencies, which causes incomplete feature representation. This study presents a novel deep-learning framework that combines an improved DenseNet for capturing local fine- grained features with a Swin Transformer for extracting global structural details and long- range relationships, thereby facilitating a more comprehensive fused output. A modified hybrid approach utilizing L1, L2 and infinity norm is used to generate attention weights in the feature fusion-oriented row-column vector dimension technique. The model is trained on different modalities in the Whole Brain Atlas dataset and the Lung-PET-CT-Dx dataset using a novel loss function. This function improves fusion by integrating pixel loss, structural similarity, and textural preservation. The evaluation of the fused image's quality involves multiple metrics that assess image clarity, structural integrity, feature retention, contrast improvement, and overall visual accuracy, providing a thorough analysis. The MSML-DenseXmer framework demonstrates improved performance compared to existing approaches across multiple medical imaging modalities. Specifically, it achieves over 9.94% rise in MRI-SPECT fusion, above 6.82% gain in MRI-PET fusion, a minimum of 18.37% increase in MRI-CT fusion, and at least 2.83% gain on the Lungs PET-CT dataset, indicating its potential in improving fusion quality.