Transcriptional Analysis of the<i>Escherichia coli mreBCD</i>Genes Responsible for Morphogenesis and Chromosome Segregation

Wachi, Masaaki; K, Osaka; Kohama, Tomoko; Sasaki, Kumi; Ohtsu, Iwao; Iwai, Noriko; Takada, Ayako; Nagai, Kazuo

doi:10.1271/bbb.60315

Cited by 13 publications

(23 citation statements)

References 30 publications

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“…Similarly, the mreCϽϾfrt allele could be corrected only by P lac ::mreC plasmids that carry mreD in cis (pCH244 or pFB121) or when mreD was coexpressed in trans from pFB128 (P R ::mreD). Others previously noted that frameshift or frt deletion-replacement lesions in mreB are polar on the expression of mreC and mreD (61,86). Our complementation results are consistent with this and further show that the chromosomal mreCϽϾfrt lesion (Fig.…”

Section: Resultssupporting

confidence: 92%

“…However, Kruse et al did not consider frtassociated polarity in the mre operon, leaving the possibility that only the loss of MreD affected viability (49). The transduction results obtained by Wachi et al are more convincing, although it is unclear whether each of the mre plasmids used in their study would be capable of correcting the corresponding mre lesion(s) in the chromosome (86). Our complementation and depletion results are comprehensive and show quite conclusively that each of the three Mre proteins is indeed required for normal viability.…”

Section: Resultsmentioning

confidence: 94%

“…Others recently concluded that all three mre genes are also essential for viability (49,86). However, Kruse et al did not consider frtassociated polarity in the mre operon, leaving the possibility that only the loss of MreD affected viability (49).…”

Section: Resultsmentioning

confidence: 99%

“…Loss of the Mre proteins has variously been reported to yield stably propagating spheres (50,61,70,84) or to be lethal (49,86), unless cells are supplied with extra copies of ftsQAZ (49). Inactivation of PBP2 and/or RodA, by treatment of wild-type (wt) cells with amdinocillin or by mutation of mrdA or mrdB, typically results in the formation of giant nondividing spheroids/spheres, which eventually lyse and die (5,62,76,82).…”

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confidence: 99%

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Conditional Lethality, Division Defects, Membrane Involution, and Endocytosis inmreandmrdShape Mutants ofEscherichia coli

2008

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Maintenance of rod shape in Escherichia coli requires the shape proteins MreB, MreC, MreD, MrdA (PBP2), and MrdB (RodA). How loss of the Mre proteins affects E. coli viability has been unclear. We generated Mre and Mrd depletion strains under conditions that minimize selective pressure for undefined suppressors and found their phenotypes to be very similar. Cells lacking one or more of the five proteins were fully viable and propagated as small spheres under conditions of slow mass increase but formed large nondividing spheroids with noncanonical FtsZ assembly patterns at higher mass doubling rates. Extra FtsZ was sufficient to suppress lethality in each case, allowing cells to propagate as small spheres under any condition. The failure of each unsuppressed mutant to divide under nonpermissive conditions correlated with the presence of elaborate intracytoplasmic membrane-bound compartments, including vesicles/vacuoles and more-complex systems. Many, if not all, of these compartments formed by FtsZ-independent involution of the cytoplasmic membrane (CM) rather than de novo. Remarkably, while some of the compartments were still continuous with the CM and the periplasm, many were topologically separate, indicating they had been released into the cytoplasm by an endocytic-like membrane fission event. Notably, cells failed to adjust the rate of phospholipid synthesis to their new surface requirements upon depletion of MreBCD, providing a rationale for the "excess" membrane in the resulting spheroids. Both FtsZ and MinD readily assembled on intracytoplasmic membrane surfaces, and we propose that this contributes significantly to the lethal division block seen in all shape mutants under nonpermissive conditions.

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Section: Resultssupporting

confidence: 92%

Section: Resultsmentioning

confidence: 94%

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

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Conditional Lethality, Division Defects, Membrane Involution, and Endocytosis inmreandmrdShape Mutants ofEscherichia coli

2008

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“…Thus, in PFGE type A isolates, the agrBDC mutations appeared to be play an important role as a cause of agrA overexpression. To explain this fact, we thought it was important that some operon was expressed as monocistronic and polycistronic mRNA (35). We hypothesized that agrA may have both monocistronic and polycistronic mRNA.…”

Section: Discussionmentioning

confidence: 99%

Changes in the agr Locus Affect Enteritis Caused by Methicillin-Resistant Staphylococcus aureus

et al. 2009

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We studied the characteristics of methicillin (meticillin)-resistant Staphylococcus aureus (MRSA) strains that caused enteritis. In a previous report, we demonstrated that both phenotypic and genotypic changes were associated with MRSA enteritis; and we hypothesized that the accessory gene regulator (agr), which is a global regulator of staphylococcal virulence and upregulates several exoproteins, is the key factor associated with the development of MRSA enteritis. In this study, we examined 12 MRSA isolates associated with enteritis from stool samples and 17 MRSA isolates not associated with enteritis that had the following characteristics: the strains associated with enteritis had the same genotype (genotype A), as detected by pulsed-field gel electrophoresis, or the strains were isolated from stools. The differences between strains that caused enteritis and those that did not cause enteritis strains were examined by quantitative reverse transcription-PCR to assess RNAII, agrA, RNAIII, and tst expression and by sequencing of the agr locus. The levels of expression of agrA, RNAIII, and tst were higher by the MRSA isolates associated with enteritis than by the MRSA isolates not associated with enteritis, whether or not they were of the same genotype. The levels of expression of RNAII by almost all the clinical isolates were similar. Sequencing of the agr locus showed that all MRSA isolates that caused enteritis have agr mutations, whereas the MRSA isolates that did not cause enteritis, with three exceptions, did not. Many of the isolates associated with enteritis had the same mutation, especially at the C-terminal end of agrA. These results suggest a trend in which mutations in the agr locus modify the expression of agrA and RNAIII and the production of toxin, all of which may increase the virulence and influence the occurrence of MRSA enteritis.Severe postsurgical enteritis caused by methicillin (meticillin)-resistant Staphylococcus aureus (MRSA) (MRSA enteritis) was prevalent in Japan in the early 1990s. In the late 1990s, most patients with MRSA enteritis were successfully treated with vancomycin, and the number of cases with MRSA enteritis gradually decreased, but whenever it occurred, it was associated with a severe clinical course and, occasionally, death (12,28).Several studies have discussed the characteristics of isolates causing MRSA enteritis. Staphylococcal enterotoxin typing, coagulase typing, and toxic shock syndrome toxin 1 (TSST-1) titers are used as markers of MRSA enteritis (10, 30, 31). Many studies have described the phenotypes of isolates that cause enteritis, but there have been only a few reports on the genomic analysis of MRSA strains that cause enteritis (36). Our laboratory has studied the molecular epidemiology of MRSA enteritis strains by using pulsed-field gel electrophoresis (PFGE) and other methodologies for more than three decades. Our work has provided evidence that the disappearance of MRSA enteritis may have resulted from the decreased incidence of enteritis-causing clones (21)...

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RodZ, a new player in bacterial cell morphogenesis

Gerdes

2009

EMBO J

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Transcriptional Analysis of theEscherichia coli mreBCDGenes Responsible for Morphogenesis and Chromosome Segregation

Cited by 13 publications

References 30 publications

Conditional Lethality, Division Defects, Membrane Involution, and Endocytosis inmreandmrdShape Mutants ofEscherichia coli

Conditional Lethality, Division Defects, Membrane Involution, and Endocytosis inmreandmrdShape Mutants ofEscherichia coli

Changes in the agr Locus Affect Enteritis Caused by Methicillin-Resistant Staphylococcus aureus

RodZ, a new player in bacterial cell morphogenesis

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