Morphological changes and proteome response of Corynebacterium glutamicum to a partial depletion of FtsI

Abstract

In Corynebacterium glutamicum, as in many Gram-positive bacteria, the cell division gene ftsI is located at the beginning of the dcw cluster, which comprises cell division-and cell wall-related genes. Transcriptional analysis of the cluster revealed that ftsI is transcribed as part of a polycistronic mRNA, which includes at least mraZ, mraW, ftsL, ftsI and murE, from a promoter that is located upstream of mraZ. ftsI appears also to be expressed from a minor promoter that is located in the intergenic ftsL-ftsI region. It is an essential gene in C. glutamicum, and a reduced expression of ftsI leads to the formation of larger and filamentous cells. A translational GFP-FtsI fusion protein was found to be functional and localized to the mid-cell of a growing bacterium, providing evidence of its role in cell division in C. glutamicum. This study involving proteomic analysis (using 2D SDS-PAGE) of a C. glutamicum strain that has partially depleted levels of FtsI reveals that at least 20 different proteins were overexpressed in the organism. Eight of these overexpressed proteins, which include DivIVA, were identified by MALDI-TOF. Overexpression of DivIVA was confirmed by Western blotting using anti-DivIVA antibodies, and also by fluorescence microscopy analysis of a C. glutamicum RESF1 strain expressing a chromosomal copy of a divIVA-gfp transcriptional fusion. Overexpression of DivIVA was not observed when FtsI was inhibited by cephalexin treatment or by partial depletion of FtsZ.

Contribution of the Rgg Transcription Regulator to Metabolism and Virulence of Streptococcus suis Serotype 2

“…Transcripts of genes encoding the FtsE and FtsI proteins, which are responsible for the assembly of constitutive protein and the synthesis of peptidoglycan, respectively, during cell division (45), were also more abundant in the ⌬rgg mutant. It was reported previously that decreased expression of ftsI resulted in overexpression of divIVA and clear changes in the bacterial morphology of Corynebacterium glutamicum (44). Therefore, it is reasonable to speculate that transcriptional alteration of these genes, which play critical roles in the maintenance of proper cell division and shape, should be responsible for the morphological changes seen in the ⌬rgg mutants, although their concrete functions are not yet determined by experiments.…”

Cell growth and cell division in the rod-shaped actinomycete Corynebacterium glutamicum

“…glutamicum cells lose their rod shape only when they are deprived of both class A HMW-PBPs, indicating that PBP1a and PBP1b are essential for cell-wall synthesis at the poles (Valbuena et al 2007). Class B HMW-PBPs are closely associated with septal PG synthesis during cell division, with FtsI being the only essential HMW-PBP as no other protein of this type can fulfill its function (Valbuena et al 2006). In support of this hypothesis, class B HMW-PBPs interact more prominently with celldivision proteins, such as FtsZ or FtsW, whereas class A HMW-PBPs are associated with DivIVA and RodA (Valbuena et al 2007).…”

“…The earliest studies were focused on the sequencing and characterization of several corynebacterial genes present in the dcw cluster, such as ftsZ (Kobayashi et al 1997;Honrubia et al 1998), ftsI (Wijayarathna et al 2001;Valbuena et al 2006), murE (Wijayarathna et al 2001), murD, murC, and ftsQ (Wachi et al 1999;Honrubia et al 2001;Ramos et al 2004), and divIVA (Ramos et al 2003). From these studies, a transcription profile of the dcw cluster from C. glutamicum (Fig.…”

“…Of these five, two are class A HMW-PBPs (PBP1a and PBP1b) with transglycosylase and transpeptidase domains, and three are class B HMW-PBPs (FtsI, PBP2a and PBP2b) with only the transpeptidase domain characteristic of this family of proteins. Except for FtsI, which is found only at the septum (Valbuena et al 2006), all HMW-PBPs are present at both cell poles and at the septum. However, when the transpeptidase domain of the PBPs is specifically blocked by b-lactam treatment, these proteins lose their localization in the cell (Valbuena et al 2007), indicating that HMW-PBP localization is dependent upon substrate recognition.…”

Deletion of cgR_1596 and cgR_2070, Encoding NlpC/P60 Proteins, Causes a Defect in Cell Separation in Corynebacterium glutamicum R

“…Besides C. glutamicum, other Actinomycetales such as Arthorobacter, Nocardia, and Mycobacteria are known to produce V-shaped cells (9,18,28,38). Although several genes involved in cell division (13,17,20,30,34,47) and cell morphology (21,35,44,45) in C. glutamicum have been characterized, the molecular mechanism of the snapping division is still largely unknown.Cell division is achieved by the consecutive actions of cell extension, chromosome replication and segregation, and cell separation. In most prokaryotic and eukaryotic species, cell separation starts by constriction and the subsequent formation of two equivalent daughter cells.…”