Characterization of divIVA and Other Genes Located in the Chromosomal Region Downstream of the dcw Cluster in Streptococcus pneumoniae

Abstract

We analyzed the chromosome region of Streptococcus pneumoniae located downstream of the division and cell wall (dcw) cluster that contains the homolog of the Bacillus subtilis cell division gene divIVA and some genes of unknown function. Inactivation of divIVA in S. pneumoniae resulted in severe growth inhibition and defects in cell shape, nucleoid segregation, and cell division. Inactivation of the ylm genes resulted in some morphological and/or division abnormalities, depending on the inactivated gene. Transcriptional analysis revealed a relationship between these genes and the ftsA and ftsZ cell division genes, also indicating that the connection between the dcw cluster and the divIVA region is more extensive than just chromosomal position and gene organization.Historically, most of the available information about bacterial cell division comes from the intensively studied gramnegative rod Escherichia coli and the gram-positive rod Bacillus subtilis (reviewed in references 1, 9, 10, 15, 17, and 24). This situation is changing, due to both the increasing interest in the field of cell division and the availability of genomic data. Most of the cell division genes have now been identified in a wide range of bacteria, and despite the differences observed among species, many of these genes are found organized in a chromosomal region corresponding to the 2-min region of the E. coli chromosome known as the dcw (for "division and cell wall") cluster.Notwithstanding the large amount of sequence information, very little is known about the molecular mechanism that regulates cell division in bacteria other than the model organisms and cell division in gram-positive cocci remains poorly understood. However, some extrapolations from the analysis of the Fts proteins that are essential for cell division, in particular the FtsZ protein, the major component of the septal ring structure (15), suggest that the basic mechanism involved in septum formation should not differ from cocci to rods.A more intriguing problem and one that shows significantly less conservation is how different bacteria operate the division site selection mechanism that ensures correct FtsZ positioning at midcell. In E. coli, the correct division site at the center is distinguished from the other potential division sites at the poles through the combined action of three proteins, MinC, MinD, and MinE, encoded by the minCDE genes (5, 6, 21).In B. subtilis, divIVB encodes the MinC and MinD homologs but not the MinE homolog (13, 26). The DivIVA protein has been proposed to play a role in the control of division site selection as the functional counterpart of the missing MinE in B. subtilis (3,7,18,19). Recently, we identified a Streptococcus pneumoniae gene encoding the B. subtilis DivIVA homolog (20). We noted that divIVA is the last gene of a region located downstream of the cell division genes ftsA to ftsZ and is conserved in the same position in a number of gram-positive cocci. In addition to divIVA, the region contains some open reading frames of unknown fu...

Control of cell division in Streptococcus pneumoniae by the conserved Ser/Thr protein kinase StkP

“…33), the cell-division phenotype of mutants lacking functional StkP cannot be ascribed solely to the lack of phosphorylation of DivIVA, because a divIVA-null mutant shows a distinguishably different phenotype with rounder and unseparated cells instead of elongated cells (50). Preliminary studies based on the in vivo effects of DivIVA mutant derivatives in key amino acid residues that abolish phosphorylation and/or mimic constitutive phosphorylation agree with this interpretation.…”

FtsZ and the division of prokaryotic cells and organelles

“…6). 114 and are often present in plants and algae 61 , indicating that they might be involved in plastid division.…”

“…Recently, several additional cell-division genes have been discovered in cyanobacteria. Some of these, including the ylm genes, are conserved throughout most bacteria 114 and are often present in plants and algae 61 , indicating that they might be involved in plastid division.…”

“…6). 114 and are often present in plants and algae 61 , indicating that they might be involved in plastid division.As in bacteria, plastid FtsZ has the potential to localize in a cytoskeletal-like array. An extensive network of filamentous structures is formed by FtsZ-GFP and a similar network is observed in electron micrographs 115 .…”

Enterococcus faecalis divIVA: an essential gene involved in cell division, cell growth and chromosome segregation

“…Recently, Pinho & Errington (2004) reported that disruption of divIVA in Staphylococcus aureus did not have an effect on chromosome segregation or cell morphology. In contrast, inactivation of divIVA in S. pneumoniae resulted in severe growth inhibition, producing defects in cell shape, nucleoid segregation and cell division (Fadda et al, 2003). It was also revealed that S. pneumoniae divIVA is co-transcribed with other genes likely to be involved in cell division (Fadda et al, 2003).…”