Faculty Opinions recommendation of Stable inheritance of Sinorhizobium meliloti cell growth polarity requires an FtsN-like protein and an amidase.

ABSTRACT Sinorhizobium meliloti is an alphaproteobacterium belonging to the Rhizobiales. Bacteria from this order elongate their cell wall at the new cell pole, generated by cell division. Screening for protein interaction partners of the previously characterized polar growth factors RgsP and RgsM, we identified the inner membrane components of the Tol-Pal system (TolQ and TolR) and novel Rgs (rhizobial growth and septation) proteins with unknown functions. TolQ, Pal, and all Rgs proteins, except for RgsE, were indispensable for S. meliloti cell growth. Six of the Rgs proteins, TolQ, and Pal localized to the growing cell pole in the cell elongation phase and to the septum in predivisional cells, and three Rgs proteins localized to the growing cell pole only. The putative FtsN-like protein RgsS contains a conserved SPOR domain and is indispensable at the early stages of cell division. The components of the Tol-Pal system were required at the late stages of cell division. RgsE, a homolog of the Agrobacterium tumefaciens growth pole ring protein GPR, has an important role in maintaining the normal growth rate and rod cell shape. RgsD is a periplasmic protein with the ability to bind peptidoglycan. Analysis of the phylogenetic distribution of the Rgs proteins showed that they are conserved in Rhizobiales and mostly absent from other alphaproteobacterial orders, suggesting a conserved role of these proteins in polar growth. IMPORTANCE Bacterial cell proliferation involves cell growth and septum formation followed by cell division. For cell growth, bacteria have evolved different complex mechanisms. The most prevalent growth mode of rod-shaped bacteria is cell elongation by incorporating new peptidoglycans in a dispersed manner along the sidewall. A small share of rod-shaped bacteria, including the alphaproteobacterial Rhizobiales, grow unipolarly. Here, we identified and initially characterized a set of Rgs (rhizobial growth and septation) proteins, which are involved in cell division and unipolar growth of Sinorhizobium meliloti and highly conserved in Rhizobiales. Our data expand the knowledge of components of the polarly localized machinery driving cell wall growth and suggest a complex of Rgs proteins with components of the divisome, differing in composition between the polar cell elongation zone and the septum.

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Stable inheritance of Sinorhizobium meliloti cell growth polarity requires an FtsN-like protein and an amidase

Nature Communications ◽

10.1038/s41467-020-20739-3 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Elizaveta Krol ◽

Lisa Stuckenschneider ◽

Joana M. Kästle Silva ◽

Peter L. Graumann ◽

Anke Becker

Keyword(s):

Cell Division ◽

Cell Polarity ◽

Chromosome Segregation ◽

Cell Elongation ◽

Sinorhizobium Meliloti ◽

Growth Zone ◽

Cell Pole ◽

Growth Polarity ◽

Selection Of

AbstractIn Rhizobiales bacteria, such as Sinorhizobium meliloti, cell elongation takes place only at new cell poles, generated by cell division. Here, we show that the role of the FtsN-like protein RgsS in S. meliloti extends beyond cell division. RgsS contains a conserved SPOR domain known to bind amidase-processed peptidoglycan. This part of RgsS and peptidoglycan amidase AmiC are crucial for reliable selection of the new cell pole as cell elongation zone. Absence of these components increases mobility of RgsS molecules, as well as abnormal RgsS accumulation and positioning of the growth zone at the old cell pole in about one third of the cells. These cells with inverted growth polarity are able to complete the cell cycle but show partially impaired chromosome segregation. We propose that amidase-processed peptidoglycan provides a landmark for RgsS to generate cell polarity in unipolarly growing Rhizobiales.

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The Sinorhizobium medicae WSM419 lpiA gene is transcriptionally activated by FsrR and required to enhance survival in lethal acid conditions

Microbiology ◽

10.1099/mic.0.28764-0 ◽

2006 ◽

Vol 152 (10) ◽

pp. 3049-3059 ◽

Cited By ~ 31

Author(s):

Wayne G. Reeve ◽

Lambert Bräu ◽

Joanne Castelli ◽

Giovanni Garau ◽

Christian Sohlenkamp ◽

...

Keyword(s):

Cell Growth ◽

Sinorhizobium Meliloti ◽

Calcium Concentration ◽

Transmembrane Protein ◽

Sequence Similarity ◽

Membrane Lipid ◽

Start Codon ◽

Major Constituent ◽

Rhizobium Tropici ◽

Sinorhizobium Medicae

Sinorhizobium medicae WR101 was identified as a mutant of WSM419 that contained a minitransposon-induced transcriptional gusA fusion activated at least 20-fold at pH 5.7. The expression of this fusion in moderately acid conditions was dependent on the calcium concentration; increasing the calcium concentration to enhance cell growth and survival in acid conditions decreased the expression of the fusion. A gene region containing the gusA fusion was sequenced, revealing five S. medicae genes: tcsA, tcrA, fsrR, lpiA and acvB. The gusA reporter in WR101 was fused to lpiA, which encodes a putative transmembrane protein also found in other Alphaproteobacteria such as Sinorhizobium meliloti, Rhizobium tropici and Agrobacterium tumefaciens. As LpiA has partial sequence similarity to the lysyl-phosphatidylglycerol (LPG) synthetase FmtC/MprF from Staphylococcus aureus, membrane lipid compositions of S. medicae strains were analysed. Cells cultured under neutral or acidic growth conditions did not induce any detectable LPG and therefore this lipid cannot be a major constituent of S. medicae membranes. Expression studies in S. medicae localized the acid-activated lpiA promoter within a 372 bp region upstream of the start codon. The acid-activated transcription of lpiA required the fused sensor–regulator product of the fsrR gene, because expression of lpiA was severely reduced in an S. medicae fsrR mutant. S. meliloti strain 1021 does not contain fsrR and acid-activated expression of the lpiA-gusA fusion did not occur in this species. Although acid-activated lpiA transcription was not required for cell growth, its expression was crucial in enhancing the viability of cells subsequently exposed to lethal acid (pH 4.5) conditions.

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A role for gibberellic acid in orienting microtubules and regulating cell growth polarity in the maize root cortex

Planta ◽

10.1007/bf00199744 ◽

1993 ◽

Vol 191 (2) ◽

pp. 149-157 ◽

Cited By ~ 52

Author(s):

F. Baluška ◽

J. S. Parker ◽

P. W. Barlow

Keyword(s):

Cell Growth ◽

Gibberellic Acid ◽

Maize Root ◽

Root Cortex ◽

Growth Polarity

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Tol-Pal system and Rgs proteins interact to promote unipolar growth and cell division in Sinorhizobium meliloti

10.1101/2020.02.13.948760 ◽

2020 ◽

Author(s):

Elizaveta Krol ◽

Hamish C. L. Yau ◽

Marcus Lechner ◽

Simon Schäper ◽

Gert Bange ◽

...

Keyword(s):

Cell Wall ◽

Cell Division ◽

Cell Growth ◽

Cell Elongation ◽

Sinorhizobium Meliloti ◽

Normal Growth ◽

Rgs Proteins ◽

Polar Growth ◽

Cell Pole ◽

Growing Cell

ABSTRACTSinorhizobium meliloti is an α-proteobacterium belonging to the Rhizobiales. Bacteria from this order elongate their cell wall at the new cell pole, generated by cell division. Screening for protein interaction partners of the previously characterized polar growth factors RgsP and RgsM, we identified the inner membrane components of the Tol-Pal system (TolQ and TolR) and novel Rgs (rhizobial growth and septation) proteins with unknown functions. TolQ, Pal and all Rgs proteins, except for RgsE, were indispensable for S. meliloti cell growth. Six of the Rgs proteins, TolQ and Pal localized to the growing cell pole in the cell elongation phase and to the septum in pre-divisional cells, and three Rgs proteins localized to growing cell pole only. The FtsN-like protein RgsS contains a conserved SPOR domain and is indispensable at the early stages of cell division. The components of the Tol-Pal system were required at the late stages of cell division. RgsE, a homolog of the Agrobacterium tumefaciens growth pole ring protein GPR, has an important role in maintaining the normal growth rate and rod cell shape. RgsD is a novel periplasmic protein with the ability to bind peptidoglycan. Analysis of the phylogenetic distribution of novel Rgs proteins showed that they are conserved in Rhizobiales and mostly absent from other α-proteobacterial orders, suggesting a conserved role of these proteins in polar growth.IMPORTANCEBacterial cell proliferation involves cell growth and septum formation followed by cell division. For cell growth, bacteria have evolved different complex mechanisms. The most prevalent growth mode of rod shaped bacteria is cell elongation by incorporating new peptidoglycan in a dispersed manner along the sidewall. A small share of rod-shaped bacteria, including the α-proteobacterial Rhizobiales, grow unipolarly. Here, we identified and initially characterized a set of Rgs (rhizobial growth and septation) proteins, which are involved in cell division and unipolar growth of Sinorhizobium meliloti and highly conserved in Rhizobiales. Our data expand the knowledge of components of the polarly localized machinery driving cell wall growth and suggest a complex of Rgs proteins with components of the divisome, differing in composition between the polar cell elongation zone and the septum.

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Two New Sinorhizobium meliloti LysR-Type Transcriptional Regulators Required for Nodulation

Journal of Bacteriology ◽

10.1128/jb.187.13.4562-4572.2005 ◽

2005 ◽

Vol 187 (13) ◽

pp. 4562-4572 ◽

Cited By ~ 44

Author(s):

Li Luo ◽

Shi-Yi Yao ◽

Anke Becker ◽

Silvia Rüberg ◽

Guan-Qiao Yu ◽

...

Keyword(s):

Cell Growth ◽

Type Strain ◽

Sinorhizobium Meliloti ◽

Wild Type Strain ◽

Nitrogenase Activity ◽

Transcriptional Regulators ◽

Wild Type ◽

Free Living ◽

Multiple Points ◽

Regulator Genes

ABSTRACT The establishment of an effective nitrogen-fixing symbiosis between Sinorhizobium meliloti and its legume host alfalfa (Medicago sativa) depends on the timely expression of nodulation genes that are controlled by LysR-type regulators. Ninety putative genes coding for LysR-type transcriptional regulators were identified in the recently sequenced S. meliloti genome. All 90 putative lysR genes were mutagenized using plasmid insertions as a first step toward determining their roles in symbiosis. Two new LysR-type symbiosis regulator genes, lsrA and lsrB, were identified in the screening. Both the lsrA and lsrB genes are expressed in free-living S. meliloti cells, but they are not required for cell growth. An lsrA1 mutant was defective in symbiosis and elicited only white nodules that exhibited no nitrogenase activity. Cells of the lsrA1 mutant were recovered from the white nodules, suggesting that the lsrA1 mutant was blocked early in nodulation. An lsrB1 mutant was deficient in symbiosis and elicited a mixture of pink and white nodules on alfalfa plants. These plants exhibited lower overall nitrogenase activity than plants inoculated with the wild-type strain, which is consistent with the fact that most of the alfalfa plants inoculated with the lsrB1 mutant were short and yellow. Cells of the lsrB1 mutant were recovered from both pink and white nodules, suggesting that lsrB1 mutants could be blocked at multiple points during nodulation. The identification of two new LysR-type symbiosis transcriptional regulators provides two new avenues for understanding the complex S. meliloti-alfalfa interactions which occur during symbiosis.

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Electron Microscopic Study of the Epithelium of the Seminal Vesicle of Aging Rats

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100050706 ◽

1974 ◽

Vol 32 ◽

pp. 138-139

Author(s):

V. F. Allison ◽

G. C. Fink ◽

G. W. Cearley

Keyword(s):

Cell Growth ◽

Epithelial Cell ◽

Epithelial Cells ◽

Seminal Vesicle ◽

Seminal Vesicles ◽

Epithelial Layer ◽

Epithelial Hyperplasia ◽

Electron Microscopic ◽

Aging Rats ◽

Pseudostratified Epithelium

It is well known that epithelial hyperplasia (benign hypertrophy) is common in the aging prostate of dogs and man. In contrast, little evidence is available for abnormal epithelial cell growth in seminal vesicles of aging animals. Recently, enlarged seminal vesicles were reported in senescent mice, however, that enlargement resulted from increased storage of secretion in the lumen and occurred concomitant to epithelial hypoplasia in that species.The present study is concerned with electron microscopic observations of changes occurring in the pseudostratified epithelium of the seminal vescles of aging rats. Special attention is given to certain non-epithelial cells which have entered the epithelial layer.

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