Conditional surface structure mutants of Caulobacter crescentus temperature-sensitive flagella formation due to an altered flagellin monomer

Marino, Bill; Ammer, Susan; Shapiro, Lucille

doi:10.1016/s0022-2836(76)80021-6

Cited by 23 publications

(27 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Although (10,21,28), the biosynthesis and regulation of stalk formation are not well defined. The apparent requirement for SecA function for stalk biogenesis revealed in this study suggests that proteins necessary for stalk formation require SecA-mediated protein translocation.…”

Section: Discussionmentioning

confidence: 99%

Cell cycle arrest of a Caulobacter crescentus secA mutant

Kang

Shapiro

1994

J Bacteriol

View full text Add to dashboard Cite

Cell differentiation is an inherent component of the Caulobacter crescentus cell cycle. The transition of a swarmer cell, with a single polar flagellum, into a sessile stalked cell includes several morphogenetic events.These include the release of the flagellum and pili, the proteolysis of chemotaxis proteins, the biogenesis of the polar stalk, and the initiation of DNA replication. We have isolated a group of temperature-sensitive mutants that are unable to complete this process at the restrictive temperature. We show here that one of these strains has a mutation in a homolog of the Escherichia coli secA gene, whose product is involved in protein translocation at the cell membrane. This C. crescentus secA mutant has allowed the identification of morphogenetic events in the swarmer-to-stalked cell transition that require SecA-dependent protein translocation. Upon shift to the nonpermissive temperature, the mutant secA swarmer cell is able to release the polar flagellum, degrade chemoreceptors, and initiate DNA replication, but it is unable to form a stalk, complete DNA replication, or carry out cell division. At the nonpermissive temperature, the cell cycle blocks prior to the de novo synthesis of flagella and chemotaxis proteins that normally occurs in the predivisional cell. Although interactions between the chromosome and the cytoplasmic membrane are believed to be a functional component of the temporal regulation of DNA replication, the ability of this secA mutant to initiate replication at the nonpermissive temperature suggests that SecA-dependent events are not involved in this process. However, both cell division and stalk formation, which is analogous to a polar division event, require SecA function.Caulobacter crescentus is a gram-negative bacterium that divides asymmetrically to produce two different types of cells: a motile swarmer cell and a sessile stalked cell (see Fig. 9) (13, 24). These cell types differ not only in their cell morphologies but also in their developmental programs. While the progeny stalked cell immediately initiates DNA replication and subsequent cell division, the swarmer cell cannot undergo DNA replication and cell division until it differentiates into a stalked cell.The swarmer-to-stalked cell differentiation is a multistep process. The flagellum of a swarmer cell is shed, and a stalk is formed at the site previously occupied by the flagellum (35). Several chemotaxis proteins are specifically degraded at this stage by a temporally controlled proteolytic activity, which may also contribute to the concomitant release of the flagellum (2,14). In addition, the sedimentation coefficient of the quiescent swarmer cell chromosome dramatically decreases as the swarmer cell differentiates into the stalked cell (9,13,41). An unknown cue signals the initiation of DNA replication in the stalked cell (3,20). This swarmer-to-stalked cell transition provides a tractable system with which to study the factors that trigger cellular differentiation events and the initiation of chromosome replica...

show abstract

Section: Discussionmentioning

confidence: 99%

Cell cycle arrest of a Caulobacter crescentus secA mutant

Kang

Shapiro

1994

J Bacteriol

View full text Add to dashboard Cite

show abstract

Section: Methodsmentioning

confidence: 99%

“…A number of nonmotile strains of C. crescentus which divide normally have been isolated (18,19). The best characterized of these strains contains a temperature sensitive mutation in the structural gene forflagellin (18). At the nonpermissive temperature, this mutant is unable to assemble flagella, but DNA synthesis and cell division occur normally (18).…”

Section: Methodsmentioning

confidence: 99%

“…The best characterized of these strains contains a temperature sensitive mutation in the structural gene forflagellin (18). At the nonpermissive temperature, this mutant is unable to assemble flagella, but DNA synthesis and cell division occur normally (18). We have extended this investigation to the role of flagellin synthesis in cell division by using a radioimmune precipitation assay to detect flagellin in several nonmotile mutants.…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Mutational analysis of developmental control in Caulobacter crescentus.

Osley¹,

Newton²

1977

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

The relationship between the cell cycle and control of development has been studied by a genetic analysis of Caulobacter crescentus. The behavior of conditional cell division mutants showed that cell cycle events, such as DNA replication and cell division, are organized into a dependent pathway(s), i.e., later.steps cannot proceed until earlier ones are completed. The ability of these strains to develop normally under nonpermissive conditions suggested that flagellin synthesis and stalk formation are dependent on the completion of different cell-cycle steps: the periodicity of flagellin synthesis is achieved by coupling it to either DNA chain elongation or completion, and stalk formation is dependent on a later step in the cell-division pathway. These developmental events are not themselves required for cell division, however. Differentiation at the cellular level is characterized by the formation of new cell types. This aspect of development is clearest in systems where asymmetric or unequal cell division takes place, e.g., grasshopper neuroblasts (1), blue green algae (2), and Caulobacter crescentus (3). We have used C. crescentus as a model system to study the control of cellular differentiation because it is a prokaryote with a small genome, the stages of its development can be easily followed, and cell types can be isolated in pure form (4-6). The life cycle of this aquatic bacterium contains two principal developmental sequences: (i) syn.thesis by the stalked cell (Fig. 1A) of the structuresflagellum, pili and holdfast-that will become part of a swarmer cell (Fig. IC) at division (swarmer cell development), and (ii). loss of motility and stalk formation by the swarmer cell as it differentiates into a new stalked cell ( Fig. iD; stalked cell development).The direct structural role of unequal cell division in the formation of a new cell type, and the observation that penicillin, a drug which blocks division in many bacteria, also prevents stalk formation in C. crescentus (8) (Ilford, Ltd.). RESULTS Identification of conditional cell-cycle mutantsApproximately 400 independent,. heat-sensitive strains were isolated from C. crescentus strain PCi by their inability to form colonies at an elevated temperature (360 or 370). These strains were screened to identify conditional cell-cycle mutants that accumulated at a characteristic phenotype at the nonpermissive temperature (Materials and Methods). Strains used were selected according to the following criteria: (a) cell division, as determined by particle count on a Coulter Counter, stopped within one generation time at 370 to produce a uniformly filamentous cell culture; (b) the rates of growth at 300 and 370 were comparable to those in the parent strain for at least two generations; and (c) cell morphology and motility were normal at 30'. Genetic analysis of the mutants showed that the reversion frequencies ranged from 10-6 to 10-8, values consistent with single-site mutations (unpublished).

show abstract

“…The simplest model assumes that essential stalk biosynthesis genes are not transcribed by crS4-RNA polymerase holoenzyme but that 0 .54 is required for a signal essential for stalk biosynthesis under normal conditions. Stalkless or stalk elongation mutants of C. crescentus have been identified previously (Schmidt 1968(Schmidt , 1969Marino et al 1976;Fukuda et al 1977;Ely et al 1984;Sommer and Newton 1989), but all of them are able to synthesize flagella. The rpoN mutant also differs from the stalkless ple mutants that were isolated on the basis of their resistance to DNA phage qbCbK infection (Fukuda et al 1977;Ely et al 1984;Sommer and Newton 1989), because we have shown that a rpoN::Tn5 disruption mutant is still sensitive to 6CbK infection.…”

Section: O ~4 Is Required For Cell Cycle-dependent Stalk Biosynthesismentioning

confidence: 99%