Genes Important for Catalase Activity in Enterococcus faecalis

Little in general is known about how heme proteins are assembled from their constituents in cells. The Gram-positive bacterium Enterococcus faecalis cannot synthesize heme and does not depend on it for growth. However, when supplied with heme in the growth medium the cells can synthesize two heme proteins; catalase (KatA) and cytochrome bd (CydAB). To identify novel factors important for catalase biogenesis libraries of E. faecalis gene insertion mutants were generated using two different types of transposons. The libraries of mutants were screened for clones deficient in catalase activity using a colony zymogram staining procedure. Analysis of obtained clones identified, in addition to katA (encoding the catalase enzyme protein), nine genes distributed over five different chromosomal loci. No factors with a dedicated essential role in catalase biogenesis or heme trafficking were revealed, but the results indicate the RNA degradosome (srmB, rnjA), an ABC-type oligopeptide transporter (oppBC), a two-component signal transducer (etaR), and NADH peroxidase (npr) as being important for expression of catalase activity in E. faecalis. It is demonstrated that catalase biogenesis in E. faecalis is independent of the CydABCD proteins and that a conserved proline residue in the N-terminal region of KatA is important for catalase assembly

Rational Design of a Plasmid Origin That Replicates Efficiently in Both Gram-Positive and Gram-Negative Bacteria

Background: Most plasmids replicate only within a particular genus or family

Regulation of virulence gene expression in Streptococcus pyogenes: Determinants of differential mRNA decay

Differential mRNA stability is an important mechanism for regulation of virulence factors in Streptococcus pyogenes (group A streptococcus, GAS), a serious and prevalent human pathogen. We have described 2 Classes of mRNA in GAS that are distinguishable by (1) stability in the stationary phase of growth, (2) kinetics of decay in exponential phase and (3) effect of depletion of RNases J1 and J2 and polynucleotide phosphorylase (PNPase) on decay in exponential phase. We discuss features of the structure of an mRNA that appear to be important for determining the Class to which it belongs and present a model to explain differential mRNA decay