Journal Article

Regions of Bacteriophage T4 and RB69 RegA Translational Repressor Proteins that Determine RNA-Binding Specificity

Miller, Eric S., Jozwik, Catherine E.

1992

Overview

RegA protein of T4 and related bacteriophages is a highly conserved RNA-binding protein that represses the translation of many phage mRNAs that encode enzymes involved in DNA metabolism. RB69, a T4-related bacteriophage, has a unique regA gene, which we have cloned, sequenced, and expressed. The predicted amino acid sequence of RB69 RegA is 78% identical to that of T4 RegA. Plasmidencoded RB69 RegA expressed in vivo represses the translation of T4 early mRNAs, including those of rIIA, rIIB, 44, 45, rpbA, and regA. Nucleotide sequences were determined for several T4 and RB69 regA mutations, and their corresponding repressor properties were characterized. All of the 10 missense mutations affect residues conserved between RB69 and T4 RegA. Two regions of RegA are especially sensitive to mutation: one between Val-15 and Ala-25 and another between Arg-70 and Ser-73. Sequence alignments and mutational data suggest that the region from Val-15 to Ala-25 is similar to helix-turn-helix domains of DNA-binding proteins and confers RNA-binding specificity upon RegA. The RegA691 protein (IIe-24 → Thr) has an in vivo phenotype that appears to distinguish site-specific and cooperative binding modes of hierarchical RegA-mediated translational repression.

• Publisher: National Academy of Sciences of the United States of America,National Acad Sciences
• Subject: Alleles / Amino Acid Sequence / Amino acids / Bacteriophages / Base Sequence / Biological and medical sciences / Cloning, Molecular / Fundamental and applied biological sciences. Psychology / Gene Expression Regulation, Viral / genes / Genes, Viral / Genetic mutation / Messenger RNA / Molecular and cellular biology / Molecular genetics / Molecular Sequence Data / Mutation / nucleotide sequence / Nucleotides / Operator regions / phage T4 / Plasmids / predictions / Protein Biosynthesis / regA gene / Repression / Repressor Proteins - chemistry / RNA / RNA, Messenger - metabolism / RNA-binding protein / RNA-Binding Proteins - chemistry / RNA-Binding Proteins - metabolism / Sequence Alignment / Structure-Activity Relationship / T-Phages - genetics / Translation. Translation factors. Protein processing / Viral Proteins - chemistry / Viral Structural Proteins - genetics