Coordination of Division and Development Influences Complex Multicellular Behavior in Agrobacterium tumefaciens

Kim, Jinwoo; Heindl, Jason E.; Fuqua, Clay

doi:10.1371/journal.pone.0056682

Cited by 53 publications

(90 citation statements)

References 73 publications

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“…Both holdfast and UPP play essential roles in attachment and biofilm formation (25,26,62,63). Finally, we have identified a gene cluster with similarity to the upp biosynthesis cluster ( , which are suggestive of cell cycle regulation of polysaccharide biosynthesis, as has been described for holdfast (64,65) and suggested for A. tumefaciens UPP (11). Because the putative P. hirschii UPP biosynthesis cluster is missing a flippase (see Fig.…”

Section: Discussionsupporting

confidence: 60%

“…Furthermore, genes shown to be essential for cell cycle progression in C. crescentus have also been shown to have important functions in cell cycle regulation of Agrobacterium tumefaciens (9)(10)(11)(12), Sinorhizobium meliloti (3,(13)(14)(15)(16), and Brucella abortus (14,(17)(18)(19)(20). Notably, the essentiality and regulons of cell cycle regulators are varied in Alphaproteobacteria, suggesting that mechanisms of cell cycle regulation are plastic and may provide a means of adapting to a particular environment (12,15,21).…”

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confidence: 99%

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Short-Stalked Prosthecomicrobium hirschii Cells Have a Caulobacter-Like Cell Cycle

et al. 2016

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The dimorphic alphaproteobacterium Prosthecomicrobium hirschii has both short-stalked and long-stalked morphotypes. Notably, these morphologies do not arise from transitions in a cell cycle. Instead, the maternal cell morphology is typically reproduced in daughter cells, which results in microcolonies of a single cell type. In this work, we further characterized the shortstalked cells and found that these cells have a Caulobacter-like life cycle in which cell division leads to the generation of two morphologically distinct daughter cells. Using a microfluidic device and total internal reflection fluorescence (TIRF) microscopy, we observed that motile short-stalked cells attach to a surface by means of a polar adhesin. Cells attached at their poles elongate and ultimately release motile daughter cells. Robust biofilm growth occurs in the microfluidic device, enabling the collection of synchronous motile cells and downstream analysis of cell growth and attachment. Analysis of a draft P. hirschii genome sequence indicates the presence of CtrA-dependent cell cycle regulation. This characterization of P. hirschii will enable future studies on the mechanisms underlying complex morphologies and polymorphic cell cycles. IMPORTANCEBacterial cell shape plays a critical role in regulating important behaviors, such as attachment to surfaces, motility, predation, and cellular differentiation; however, most studies on these behaviors focus on bacteria with relatively simple morphologies, such as rods and spheres. Notably, complex morphologies abound throughout the bacteria, with striking examples, such as P. hirschii, found within the stalked Alphaproteobacteria. P. hirschii is an outstanding candidate for studies of complex morphology generation and polymorphic cell cycles. Here, the cell cycle and genome of P. hirschii are characterized. This work sets the stage for future studies of the impact of complex cell shapes on bacterial behaviors. The Alphaproteobacteria comprise a diverse group of bacteria, including important pathogens of animals (Brucella spp. and Rickettsia spp.) and plants (Agrobacterium spp.), plant symbionts (Rhizobium spp., Sinorhizobium spp., and Mesorhizobium spp.), photosynthetic bacteria (Rhodobacter spp.), freshwater bacteria (Caulobacter spp.), and marine bacteria (Hyphomonas spp.). Despite the diverse habitats and lifestyles of these bacteria, many alphaproteobacterial species have a characteristic life cycle that culminates in asymmetric cell division (1-4). Caulobacter crescentus has served as a model bacterial system for the study of cell cycle regulation, and decades of research have provided insights into the mechanism underlying the precise cell cycle control that allows

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Section: Discussionsupporting

confidence: 60%

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confidence: 99%

Short-Stalked Prosthecomicrobium hirschii Cells Have a Caulobacter-Like Cell Cycle

et al. 2016

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“…Indeed, in S. meliloti, PodJ1 is suggested to play a critical role in PleC Sm signaling, and PleC Sm is essential for cell viability and may play a role in cell division (20). By analogy, PodJ At may influence the localization or activity of components of the cell division and development regulatory pathway, for example, PleC (Atu0982) or DivK (Atu1296) (41). Additionally, PodJ At is longer (1,248 amino acids [aa]) than PodJ Cc (974 aa) and may have additional functions.…”

Section: Resultsmentioning

confidence: 99%

Loss of PodJ in Agrobacterium tumefaciens Leads to Ectopic Polar Growth, Branching, and Reduced Cell Division

et al. 2016

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Agrobacterium tumefaciens is a rod-shaped Gram-negative bacterium that elongates by unipolar addition of new cell envelope material. Approaching cell division, the growth pole transitions to a nongrowing old pole, and the division site creates new growth poles in sibling cells. The A. tumefaciens homolog of the Caulobacter crescentus polar organizing protein PopZ localizes specifically to growth poles. In contrast, the A. tumefaciens homolog of the C. crescentus polar organelle development protein PodJ localizes to the old pole early in the cell cycle and accumulates at the growth pole as the cell cycle proceeds. FtsA and FtsZ also localize to the growth pole for most of the cell cycle prior to Z-ring formation. To further characterize the function of polar localizing proteins, we created a deletion of A. tumefaciens podJ (podJ At ). ⌬podJ At cells display ectopic growth poles (branching), growth poles that fail to transition to an old pole, and elongated cells that fail to divide. In ⌬podJ At cells, A. tumefaciens PopZgreen fluorescent protein (PopZ At -GFP) persists at nontransitioning growth poles postdivision and also localizes to ectopic growth poles, as expected for a growth-pole-specific factor. Even though GFP-PodJ At does not localize to the midcell in the wild type, deletion of podJ At impacts localization, stability, and function of Z-rings as assayed by localization of FtsA-GFP and FtsZ-GFP. Z-ring defects are further evidenced by minicell production. Together, these data indicate that PodJ At is a critical factor for polar growth and that ⌬podJ At cells display a cell division phenotype, likely because the growth pole cannot transition to an old pole. IMPORTANCEHow rod-shaped prokaryotes develop and maintain shape is complicated by the fact that at least two distinct species-specific growth modes exist: uniform sidewall insertion of cell envelope material, characterized in model organisms such as Escherichia coli, and unipolar growth, which occurs in several alphaproteobacteria, including Agrobacterium tumefaciens. Essential components for unipolar growth are largely uncharacterized, and the mechanism constraining growth to one pole of a wild-type cell is unknown. Here, we report that the deletion of a polar development gene, podJ At , results in cells exhibiting ectopic polar growth, including multiple growth poles and aberrant localization of cell division and polar growth-associated proteins. These data suggest that PodJ At is a critical factor in normal polar growth and impacts cell division in A. tumefaciens.

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“…Furthermore, the S. meliloti pleD mutant did not differ from the wild type in motility, while the C. crescentus pleD mutant was hypermotile due to defects in flagellum ejection and stalk morphogenesis (87). Similarly to the S. meliloti pleD mutant, an A. tumefaciens pleD deletion mutant was unaffected in motility and showed no obvious developmental defects (88). However, the pattern of flagellation differs between these organisms.…”

Section: Discussionmentioning

confidence: 96%

Cyclic Di-GMP Regulates Multiple Cellular Functions in the Symbiotic Alphaproteobacterium Sinorhizobium meliloti

et al. 2016

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Sinorhizobium meliloti undergoes major lifestyle changes between planktonic states, biofilm formation, and symbiosis with leguminous plant hosts. In many bacteria, the second messenger 3=,5=-cyclic di-GMP (c-di-GMP, or cdG) promotes a sessile lifestyle by regulating a plethora of processes involved in biofilm formation, including motility and biosynthesis of exopolysaccharides (EPS). Here, we systematically investigated the role of cdG in S. meliloti Rm2011 encoding 22 proteins putatively associated with cdG synthesis, degradation, or binding. Single mutations in 21 of these genes did not cause evident changes in biofilm formation, motility, or EPS biosynthesis. In contrast, manipulation of cdG levels by overproducing endogenous or heterologous diguanylate cyclases (DGCs) or phosphodiesterases (PDEs) affected these processes and accumulation of N-Acyl-homoserine lactones in the culture supernatant. Specifically, individual overexpression of the S. meliloti genes pleD, SMb20523, SMb20447, SMc01464, and SMc03178 encoding putative DGCs and of SMb21517 encoding a single-domain PDE protein had an impact and resulted in increased levels of cdG. Compared to the wild type, an S. meliloti strain that did not produce detectable levels of cdG (cdG 0 ) was more sensitive to acid stress. However, it was symbiotically potent, unaffected in motility, and only slightly reduced in biofilm formation. The SMc01790-SMc01796 locus, homologous to the Agrobacterium tumefaciens uppABCDEF cluster governing biosynthesis of a unipolarly localized polysaccharide, was found to be required for cdG-stimulated biofilm formation, while the single-domain PilZ protein McrA was identified as a cdG receptor protein involved in regulation of motility. IMPORTANCEWe present the first systematic genome-wide investigation of the role of 3=,5=-cyclic di-GMP (c-di-GMP, or cdG) in regulation of motility, biosynthesis of exopolysaccharides, biofilm formation, quorum sensing, and symbiosis in a symbiotic alpha-rhizobial species. Phenotypes of an S. meliloti strain unable to produce cdG (cdG 0 ) demonstrated that this second messenger is not essential for root nodule symbiosis but may contribute to acid tolerance. Our data further suggest that enhanced levels of cdG promote sessility of S. meliloti and uncovered a single-domain PilZ protein as regulator of motility.

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Coordination of Division and Development Influences Complex Multicellular Behavior in Agrobacterium tumefaciens

Cited by 53 publications

References 73 publications

Short-Stalked Prosthecomicrobium hirschii Cells Have a Caulobacter-Like Cell Cycle

Short-Stalked Prosthecomicrobium hirschii Cells Have a Caulobacter-Like Cell Cycle

Loss of PodJ in Agrobacterium tumefaciens Leads to Ectopic Polar Growth, Branching, and Reduced Cell Division

Cyclic Di-GMP Regulates Multiple Cellular Functions in the Symbiotic Alphaproteobacterium Sinorhizobium meliloti

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