scholarly journals Overlap of cargo binding sites on myosin V coordinates the inheritance of diverse cargoes

2012 ◽  
Vol 198 (1) ◽  
pp. 69-85 ◽  
Author(s):  
P. Taylor Eves ◽  
Yui Jin ◽  
Matthew Brunner ◽  
Lois S. Weisman
Keyword(s):  
Cell Cycle ◽  
Cell Division ◽  
Binding Sites ◽  
Daughter Cell ◽  
Common Mechanism ◽  
Myosin V ◽  
Yeast Vacuole ◽  
Cargo Binding

During cell division, organelles are distributed to distinct locations at specific times. For the yeast vacuole, the myosin V motor, Myo2, and its vacuole-specific cargo adaptor, Vac17, regulate where the vacuole is deposited and the timing of vacuole movement. In this paper, we show that Mmr1 functions as a mitochondria-specific cargo adaptor early in the cell cycle and that Mmr1 binds Myo2 at the site that binds Vac17. We demonstrate that Vac17 and Mmr1 compete for binding at this site. Unexpectedly, this competition regulates the volume of vacuoles and mitochondria inherited by the daughter cell. Furthermore, eight of the nine known Myo2 cargo adaptors overlap at one of two sites. Vac17 and Mmr1 overlap at one site, whereas Ypt11 and Kar9 bind subsets of residues that also bind Ypt31/Ypt32, Sec4, and Inp2. These observations predict that competition for access to Myo2 may be a common mechanism to coordinate the inheritance of diverse cargoes.

scholarly journals Role of the CtrA cell cycle regulator in the bloodborne bacterial pathogen, Bartonella quintana.

2021 ◽  
Author(s):  
◽  
Robert Haydn Thomson
Keyword(s):  
Cell Cycle ◽  
Cell Division ◽  
Dna Replication ◽  
Binding Sites ◽  
Caulobacter Crescentus ◽  
Regulatory Regions ◽  
Bartonella Quintana ◽  
Cell Cycle Regulator ◽  
Wide Range

<p>Bartonella quintana is an important re-emerging human pathogen and the causative agent of trench fever. It utilizes a stealth invasion strategy to infect hosts and is transmitted by lice. Throughout infection it is crucial for the bacteria to maintain a tight regulation of cell division, to prevent immune detection and allow for transmission to new hosts. CtrA is an essential master cell cycle regulatory protein found in the alpha-proteobacteria. It regulates many genes, ensuring the appropriate timing of gene expression and DNA replication. In the model organism Caulobacter crescentus, it regulates 26% of cell cycle-regulated genes. CtrA has been reported to bind two specific DNA motifs in gene promoter regions, TTAAN7TTAAC, and TTAACCAT. Genes regulated by CtrA encode proteins with a wide range of activities, including initiation of DNA replication, cell division, DNA methylation, polar morphogenesis, flagellar biosynthesis, and cell wall metabolism. However, the role of the CtrA homologue in Bartonella spp. has not been investigated. In this project we aimed to make an initial characterisation of the master cell cycle regulator CtrA. This was done by identifying gene regulatory regions containing putative CtrA binding sites and testing for direct interactions via a -galactosidase assay. It was found B. quintana CtrA shared 81 % amino acid identity with its C. crescentus homologue. Within the genome of B. quintana str. Toulouse we discovered 21 genes containing putative CtrA binding sites in their regulatory regions. Of these genes we demonstrated interactions between CtrA and the promoter region of ftsE a cell division gene [1], hemS, and hbpC, two heme regulatory genes. We also found no evidence of CtrA regulating its own expression, which was unexpected because CtrA autoregulation has been demonstrated in C. crescentus.</p>

Protein transport and flagellum assembly dynamics revealed by analysis of the paralysed trypanosome mutant snl-1

1999 ◽  
Vol 112 (21) ◽  
pp. 3769-3777 ◽  
Author(s):  
P. Bastin ◽  
T.J. Pullen ◽  
T. Sherwin ◽  
K. Gull
Keyword(s):  
Cell Cycle ◽  
Cell Division ◽  
Trypanosoma Brucei ◽  
Daughter Cell ◽  
Protein Transport ◽  
Retrograde Transport ◽  
Transport Systems ◽  
Major Constituent ◽  
Wild Type ◽  
Detergent Extraction

The paraflagellar rod (PFR) of Trypanosoma brucei is a large, complex, intraflagellar structure that represents an excellent system in which to study flagellum assembly. Molecular ablation of one of its major constituents, the PFRA protein, in the snl-1 mutant causes considerable alteration of the PFR structure, leading to cell paralysis. Mutant trypanosomes sedimented to the bottom of the flask rather than staying in suspension but divided at a rate close to that of wild-type cells. This phenotype was complemented by transformation of snl-1 with a plasmid overexpressing an epitope-tagged copy of the PFRA gene. In the snl-1 mutant, other PFR proteins such as the second major constituent, PFRC, accumulated at the distal tip of the growing flagellum, forming a large dilation or ‘blob’. This was not assembled as filaments and was removed by detergent-extraction. Axonemal growth and structure was unmodified in the snl-1 mutant and the blob was present only at the tip of the new flagellum. Strikingly, the blob of unassembled material was shifted towards the base of the flagellum after cell division and was not detectable when the daughter cell started to produce a new flagellum in the next cell cycle. The dynamics of blob formation and regression are likely indicators of anterograde and retrograde transport systems operating in the flagellum. In this respect, the accumulation of unassembled PFR precursors in the flagellum shows interesting similarities with axonemal mutants in other systems, illustrating transport of components of a flagellar structure during both flagellum assembly and maintenance. Observation of PFR components indicate that these are likely to be regulated and modulated throughout the cell cycle.

scholarly journals Role of the CtrA cell cycle regulator in the bloodborne bacterial pathogen, Bartonella quintana.

2021 ◽  
Author(s):  
◽  
Robert Haydn Thomson
Keyword(s):  
Cell Cycle ◽  
Cell Division ◽  
Dna Replication ◽  
Binding Sites ◽  
Caulobacter Crescentus ◽  
Regulatory Regions ◽  
Bartonella Quintana ◽  
Cell Cycle Regulator ◽  
Wide Range

<p>Bartonella quintana is an important re-emerging human pathogen and the causative agent of trench fever. It utilizes a stealth invasion strategy to infect hosts and is transmitted by lice. Throughout infection it is crucial for the bacteria to maintain a tight regulation of cell division, to prevent immune detection and allow for transmission to new hosts. CtrA is an essential master cell cycle regulatory protein found in the alpha-proteobacteria. It regulates many genes, ensuring the appropriate timing of gene expression and DNA replication. In the model organism Caulobacter crescentus, it regulates 26% of cell cycle-regulated genes. CtrA has been reported to bind two specific DNA motifs in gene promoter regions, TTAAN7TTAAC, and TTAACCAT. Genes regulated by CtrA encode proteins with a wide range of activities, including initiation of DNA replication, cell division, DNA methylation, polar morphogenesis, flagellar biosynthesis, and cell wall metabolism. However, the role of the CtrA homologue in Bartonella spp. has not been investigated. In this project we aimed to make an initial characterisation of the master cell cycle regulator CtrA. This was done by identifying gene regulatory regions containing putative CtrA binding sites and testing for direct interactions via a -galactosidase assay. It was found B. quintana CtrA shared 81 % amino acid identity with its C. crescentus homologue. Within the genome of B. quintana str. Toulouse we discovered 21 genes containing putative CtrA binding sites in their regulatory regions. Of these genes we demonstrated interactions between CtrA and the promoter region of ftsE a cell division gene [1], hemS, and hbpC, two heme regulatory genes. We also found no evidence of CtrA regulating its own expression, which was unexpected because CtrA autoregulation has been demonstrated in C. crescentus.</p>

scholarly journals Effects of Chromosome Underreplication on Cell Division in Escherichia coli

1998 ◽  
Vol 180 (23) ◽  
pp. 6364-6374 ◽  
Author(s):  
Emilia Botello ◽  
Kurt Nordström
Keyword(s):  
Escherichia Coli ◽  
Cell Cycle ◽  
Cell Division ◽  
Daughter Cell ◽  
Threshold Value ◽  
Lower Probability ◽  
Mass Ratio ◽  
Distinct Cell ◽  
Delayed Initiation ◽  
Bacterial Cell Cycle

ABSTRACT The key processes of the bacterial cell cycle are controlled and coordinated to match cellular mass growth. We have studied the coordination between replication and cell division by using a temperature-controlled Escherichia coli intR1 strain. In this strain, the initiation time for chromosome replication can be displaced to later (underreplication) or earlier (overreplication) times in the cell cycle. We used underreplication conditions to study the response of cell division to a delayed initiation of replication. The bacteria were grown exponentially at 39°C (normal DNA/mass ratio) and shifted to 38 and 37°C. In the last two cases, new, stable, lower DNA/mass ratios were obtained. The rate of replication elongation was not affected under these conditions. At increasing degrees of underreplication, increasing proportions of the cells became elongated. Cell division took place in the middle in cells of normal size, whereas the longer cells divided at twice that size to produce one daughter cell of normal size and one three times as big. The elongated cells often produced one daughter cell lacking a chromosome; this was always the smallest daughter cells, and it was the size of a normal newborn cell. These results favor a model in which cell division takes place at only distinct cell sizes. Furthermore, the elongated cells had a lower probability of dividing than the cells of normal size, and they often contained more than two nucleoids. This suggests that for cell division to occur, not only must replication and nucleoid partitioning be completed, but also the DNA/mass ratio must be above a certain threshold value. Our data support the ideas that cell division has its own control system and that there is a checkpoint at which cell division may be abolished if previous key cell cycle processes have not run to completion.

scholarly journals Tracking the Biogenesis and Inheritance of Subpellicular Microtubule inTrypanosoma bruceiwith Inducible YFP-α-Tubulin

2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
Omar Sheriff ◽  
Li-Fern Lim ◽  
Cynthia Y. He
Keyword(s):  
Cell Cycle ◽  
Cell Division ◽  
Trypanosoma Brucei ◽  
Daughter Cell ◽  
Structural System ◽  
Microtubule Cytoskeleton ◽  
Asymmetric Pattern ◽  
Microtubule Formation ◽  
Attachment Zone ◽  
Mode Of Inheritance

The microtubule cytoskeleton forms the most prominent structural system inTrypanosoma brucei, undergoing extensive modifications during the cell cycle. Visualization of tyrosinated microtubules leads to a semiconservative mode of inheritance, whereas recent studies employing microtubule plus end tracking proteins have hinted at an asymmetric pattern of cytoskeletal inheritance. To further the knowledge of microtubule synthesis and inheritance duringT. bruceicell cycle, the dynamics of the microtubule cytoskeleton was visualized by inducible YFP-α-tubulin expression. During new flagellum/flagellum attachment zone (FAZ) biogenesis and cell growth, YFP-α-tubulin was incorporated mainly between the old and new flagellum/FAZ complexes. Cytoskeletal modifications at the posterior end of the cells were observed with EB1, a microtubule plus end binding protein, particularly during mitosis. Additionally, the newly formed microtubules segregated asymmetrically, with the daughter cell inheriting the new flagellum/FAZ complex retaining most of the new microtubules. Together, our results suggest an intimate connection between new microtubule formation and new FAZ assembly, consequently leading to asymmetric microtubule inheritance and cell division.

Sign in / Sign up

Export Citation Format

Share Document