New minC mutations suggest different interactions of the same region of division inhibitor MinC with proteins specific for minD and dicB coinhibition pathways

Mulder, E; Woldringh, Conrad L.; Tétart, Françoise; Bouché, Jean‐Pierre

doi:10.1128/jb.174.1.35-39.1992

Cited by 30 publications

(23 citation statements)

References 16 publications

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“…1, SB, and 6). The product of the putative B. subtilis minC gene is similar to E. coli MinC in a region that is thought to be responsible for interactions with the E. coli cell division proteins MinD and DicB (26). In agreement with the view that the B. subtilis minC-and minD-like genes are involved with septum placement, this DNA is the site of the divlVBl minicell mutation (Fig.…”

Section: Discussionsupporting

confidence: 62%

Identification of Bacillus subtilis genes for septum placement and shape determination

et al. 1992

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The Bacilus subtilis divIVBI mutation causes aberrant positioning of the septum during cell division, resulting in the formation of small, anucleate cells known as minicells. We report the cloning of the wild-type allele of divIVBI and show that the mutation lies within a stretch of DNA containing two open reading frames whose predicted products are in part homologous to the products of the Escherichia coli minicell genes minC and minD. Just upstream of minC and minD, and in the same orientation, are three genes whose products are homologous to the products of the E. coli shape-determining genes mreB, mreC, and mreD. The B. subtilis mreB, mreC, and mreD genes are the site of a conditional mutation (rodBI) that causes the production of aberrantly shaped cells under restrictive conditions. Northern (RNA) hybridization experiments and disruption experiments based on the use of integrational plasmids indicate that the mre and min genes constitute a five-cistron operon. The possible involvement of min gene products in the switch from medial to polar placement of the septum during sporulation is discussed.Cells of the gram-positive soil bacterium Bacillus subtilis are capable of entering an alternative developmental pathway that is characterized by the formation of a transverse septum. During vegetative growth, the formation of a septum at the center of the cell partitions the bacterium into identical daughter cells which separate and undergo further cycles of binary fission. The hallmark of the process of sporulation, in contrast, is the formation of a septum that is sited near one pole of the cell. This asymmetrically positioned septum partitions the bacterium into unequal-sized cellular compartments, of which one, the forespore, undergoes metamorphosis into a spore and the other, the mother cell, participates in the formation of the spore but is eventually discarded by lysis. The binary fission septum and the sporulation septum are produced by similar processes (17), involving in both cases the action of B. subtilis homologs to the Escherichia coli septation genes ftsA and ftsZ (2, 3). However, little is known about the mechanisms that govern the alternative placement of the septa at medial or polar positions within the cell.In the non-spore-forming bacterium E. coli, placement of the septum is governed by genes at the minB locus. Cells of E. coli grow by binary fission and are normally capable of producing only medially sited septa. However, certain mutations at the minB locus allow septa to form at a polar position, thereby generating small, anucleate cells with intact cell walls and membranes which except for their lack of DNA appear to be metabolically normal (1). Minicell production occurs as an alternative to normal division, and consequently, the sister cell is filamentous and carries two or more copies of the chromosome. Because the minicell division process appears to be identical to that of the wild type, the defect is apparently with site selection and not with septum formation. As with sporulation in B....

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Section: Discussionsupporting

confidence: 62%

Identification of Bacillus subtilis genes for septum placement and shape determination

et al. 1992

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“…One expectation of this hypothesis is that the region of MinC which interacts with MinD should be more conserved than the rest of the molecule. Mulder et al (30) recently identified a series of mutations within minC which suppress division inhibition induced by overexpression of minD. Significantly, these mutations cluster within the conserved region of MinC.…”

Section: Discussionmentioning

confidence: 99%

The divIVB region of the Bacillus subtilis chromosome encodes homologs of Escherichia coli septum placement (minCD) and cell shape (mreBCD) determinants

1992

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Mutation of the divIVB locus in BaciUlus subtilis causes frequent misplacement of the division septum, resulting in circular minicells, short rods, and filaments of various sizes. The divIVBI mutant allele maps to a region of the chromosome also known to encode sporulation (spoOB, spoIVF, spoIIB) and cell shape (rodB) determinants. This study reports the cloning and sequence analysis of 4.4 kb of the B. subtilis chromosome encompassing the divIVB locus. This region contains five open reading frames (ORFs) arranged in two functionally distinct gene clusters (mre and min) and transcribed colinearly with the direction of replication.Although sequence analysis reveals potential promoters preceding each gene cluster, studies with integrational plasmids suggest that all five ORFs are part of a single transcription unit. The first gene cluster contains three ORFs (mreBCD) homologous to the mre genes of Escherichia coli. We show that rodBI is allelic to mreD and identify the rodB) mutation. The second gene cluster contains two ORFs (minCD) homologous to minC and minD ofE. coli but lacks a minE homolog. We show that divIVBI is allelic to minD and identify two mutations in the divIVlBI allele. Insertional inactivation of either minC or minD or the presence of the divIVB region on plasmids produces a severe minicell phenotype in wild-type cells. Moreover, E. coli cells carrying the divIVB region on a low-copy-number plasmid produce minicells, suggesting that a product of this locus may retain some function across species boundaries.

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“…The specific glycine substitutions selected in the present study were based on previous reports in which minC Ec mutants were characterized after mutagenesis with nitrosoguanidine (12), ethyl methanesulfonate (18), or hydroxylamine (22). While many induced MinC Ec mutants had nonsense and missense mutations, several mutations involved changes from glycine (G) to charged amino acids, such aspartic acid (G10D and G171D), glutamic acid (G161E), lysine (G161K), and arginine (G176R) (18,22). In the present study, mutations at nonconserved (i.e., neutral) C-terminal residues (E144I mutation in MinC Ng and P141A mutation in MinC Ec ) were also created to validate the functional significance of mutations in conserved glycine residues of MinC.…”

Section: Resultsmentioning

confidence: 99%

“…Lutkenhaus and Sundaramoorthy (21) recently proposed that the interaction between MinC and MinD probably occurs in the cytoplasm and that the MinD-ATP-MinC complex persists because MinC does not stimulate the ATPase activity of MinD. Several spontaneous MinC Ec C-terminal mutants, including MinC Ec G161E, G171D, and G171S, have been isolated and analyzed to determine their morphological effects when they are expressed in E. coli (14,18,22,26). However, these chromosomal mutants were not tested for functionality by overexpression in E. coli or by yeast two-hybrid analyses.…”

Section: Discussionmentioning

confidence: 99%

Conserved Glycines in the C Terminus of MinC Proteins Are Implicated in Their Functionality as Cell Division Inhibitors

et al. 2004

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Alignment of 36 MinC sequences revealed four completely conserved C-terminal glycines. As MinC inhibits cytokinesis in Neisseria gonorrhoeae and Escherichia coli, the functional importance of these glycines in N. gonorrhoeae MinC (MinC Ng ) and E. coli MinC (MinC Ec ) was investigated through amino acid substitution by using site-directed mutagenesis. Each mutant was evaluated for its ability to arrest cell division and to interact with itself and MinD. In contrast to overexpression of wild-type MinC, overexpression of mutant proteins in E. coli did not induce filamentation, indicating that they lost functionality. Yeast two-hybrid studies showed that MinC Ec interacts with itself and MinD Ec ; however, no interactions involving MinC Ng were detected. Therefore, a recombinant MinC protein, with the N terminus of MinC Ec and the C terminus of MinC Ng , was designed to test for a MinC Ng -MinD Ng interaction. Each MinC mutant interacted with either MinC or MinD but not both, indicating the specificity of glycine residues for particular protein-protein interactions. Each glycine was mapped on the C-terminal surfaces (A, B, and C) of the solved Thermotoga maritima MinC structure. We found that MinC Ec G161, residing in close proximity to the A surface, is involved in homodimerization, which is essential for MinC function. Glycines corresponding to MinC Ec G135, G154, and G171, located within or adjacent to the B-C surface junction, are critical for MinC-MinD interactions. Circular dichroism revealed no gross structural perturbations of the mutant proteins, although the contribution of glycines to protein flexibility and stability cannot be discounted. Using molecular modeling, we propose that exposed conserved MinC glycines interact with exposed residues of the ␣-7 helix of MinD.

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New minC mutations suggest different interactions of the same region of division inhibitor MinC with proteins specific for minD and dicB coinhibition pathways

Cited by 30 publications

References 16 publications

Identification of Bacillus subtilis genes for septum placement and shape determination

Identification of Bacillus subtilis genes for septum placement and shape determination

The divIVB region of the Bacillus subtilis chromosome encodes homologs of Escherichia coli septum placement (minCD) and cell shape (mreBCD) determinants

Conserved Glycines in the C Terminus of MinC Proteins Are Implicated in Their Functionality as Cell Division Inhibitors

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