Identification and characterization of cell wall-cell division gene clusters in pathogenic gram-positive cocci

Abstract

Clusters of peptidoglycan biosynthesis and cell division genes (DCW genes) were identified and sequenced in two gram-positive cocci, Staphylococcus aureus and Enterococcus faecalis. The results indicated some similarities in organization compared with previously reported bacterial DCW gene clusters, including the presence of penicillin-binding proteins at the left ends and ftsA and ftsZ cell division genes at the right ends of the clusters. However, there were also some important differences, including the absence of several genes, the comparative sizes of the div1B and ftsQ genes, and a wide range of amino acid sequence similarities when the genes of the gram-positive cocci were translated and compared to bacterial homologs.Biosynthesis of peptidoglycan in bacteria is a complex process involving numerous enzymes, most of which have been shown to be essential in pathogenic bacteria (3, 16). These enzymes have been studied most extensively in Escherichia coli, and the genes which encode them have been cloned and the proteins have been characterized over the past several years (29,30). Many of these genes had been previously mapped in this organism due to the availability of temperature-sensitive lethal mutants. In E. coli, it was discovered that a number of these genes, including the one encoding penicillin-binding protein 3 (PBP3), were organized in a cluster located at 2 min on the chromosomal map (29,34). Also present in this cluster were other genes important in cell division, including ftsA and ftsZ (4,19,31). All of these genes were found to be tightly packed, with reading frames sometimes overlapping, all oriented in the same direction of transcription, and there has been speculation about possible regulation of cellular growth and division within this region. Peptidoglycan biosynthetic genes were not exclusively in this 2-min region, however, as other genes, such as murA (69.3 min; 2), murB (89.9 min; 23), and murI (dga; 89.8 min; 10, 12), were found elsewhere on the chromosome.A cluster similar to the 2-min region of E. coli was found in the gram-positive rod Bacillus subtilis (6,27). Interestingly, with a few exceptions (for example, sporulation-specific genes), the gene arrangement was quite similar to that seen in E. coli, including the tight arrangement of genes and a similar direction of transcription (7,20). However, missing from this region and located elsewhere on the chromosome were the murC, murF, and ddl genes found in the E. coli cluster. Recently, the genome sequence of another gram-negative rod, Haemophilus influenzae, was reported and the gene order in this region was found to be identical to that of E. coli (13). These findings suggest a possible evolutionary relationship for genes involved in peptidoglycan biosynthesis and cell division.The existence of similar gene clusters in gram-positive cocci has not been reported. This work describes clusters of peptidoglycan biosynthetic and cell division genes in Staphylococcus aureus and Enterococcus faecalis, and the results presented show both...

A Putatively Phase Variable Gene ( dca ) Required for Natural Competence in Neisseria gonorrhoeae but Not Neisseria meningitidis Is Located within the Division Cell Wall ( dcw ) Gene Cluster

“…However, the DNA sequence 3Ј of the putative yabB homologue includes an additional 17 tightly packed ORFs orientated in the same direction (Fig. 1), ending with ftsZ, usually ascribed as the most 3Ј gene of the dcw cluster (48). Of the 18 ORFs in this cluster, 15 encode putative proteins with homology to those encoded by dcw genes of other bacterial species (Fig.…”

“…This approach has been used to identify regions of horizontally transferred DNA in N. meningitidis MC58 (59). We used a modification of this (46), N. meningitidis strain MC58 (59), E. coli (4,64), H. influenzae (20), B. subtilis (13,38), S. aureus, and E. faecalis (48). All genes are transcribed from left to right.…”

“…The genes of this cluster are tightly packed, some overlapping, and are oriented in one direction (4,64). Although the dcw cluster is highly conserved among evolutionarily diverse bacterial species (48), some variations in the clusters have been reported. These variations include the location of some dcw genes at separate chromosomal locations, such as ftsW, murF, and ddlA of Staphylococcus aureus (48), and the addition of species-specific genes within the dcw cluster, such as spoVD and spoVE of Bacillus subtilis (12,31).…”

“…Although the dcw cluster is highly conserved among evolutionarily diverse bacterial species (48), some variations in the clusters have been reported. These variations include the location of some dcw genes at separate chromosomal locations, such as ftsW, murF, and ddlA of Staphylococcus aureus (48), and the addition of species-specific genes within the dcw cluster, such as spoVD and spoVE of Bacillus subtilis (12,31). In the case of these B. subtilis sporulation genes, spoVD (12) and spoVE (31) have homology to the dcw cluster genes pbpB and ftsW, respectively.…”

“…A potential MtrR-binding sequence was found upstream of an open reading frame (ORF) with homology to yabB of E. coli (4). A homologue of yabB is the first gene of the dcw cluster in all of the bacterial species studied to date (4,13,20,38,48,64). Since the dcw cluster of the pathogenic Neisseria spp.…”