Occurrence of Homologs of the Escherichia coli lytB Gene in Gram-Negative Bacterial Species

The Escherichia coli LytB protein regulates the activity of guanosine 3′,5′-bispyrophosphate synthetase I (RelA). A Southern blot analysis of chromosomal DNA with the E. coli lytB gene as a probe revealed the presence of lytB homologs in all of the gram-negative bacterial species examined but not in gram-positive species. The lytB homologs from Enterobacter aerogenes and Pseudomonas fluorescens complemented the E. coli lytB44 mutant allele.