scholarly journals KHARON Is an Essential Cytoskeletal Protein Involved in the Trafficking of Flagellar Membrane Proteins and Cell Division in African Trypanosomes

2016 ◽  
Vol 291 (38) ◽  
pp. 19760-19773 ◽  
Author(s):  
Marco A. Sanchez ◽  
Khoa D. Tran ◽  
Jessica Valli ◽  
Sam Hobbs ◽  
Errin Johnson ◽  
...  
Keyword(s):  
Cell Division ◽  
Membrane Proteins ◽  
Cytoskeletal Protein ◽  
African Trypanosomes ◽  
Flagellar Membrane

scholarly journals The Trypanosoma brucei Cytoskeletal Protein KHARON Associates with Partner Proteins to Mediate Both Cytokinesis and Trafficking of Flagellar Membrane Proteins

2020 ◽  
Author(s):  
Marco A. Sanchez ◽  
Scott M. Landfear
Keyword(s):  
Membrane Proteins ◽  
Trypanosoma Brucei ◽  
Tsetse Fly ◽  
Cytoskeletal Protein ◽  
Close Proximity ◽  
Flagellar Membrane ◽  
Parasite Viability ◽  
Parasite Biology ◽  
Partner Proteins ◽  
Core Activity

ABSTRACTIn the African trypanosome Trypanosoma brucei, the cytoskeletal protein TbKHARON is required for trafficking of a putative Ca2+ channel to the flagellar membrane, and it is essential for parasite viability in both the mammalian stage bloodstream forms and the tsetse fly procyclic forms. This protein is located at the base of the flagellum, in the pellicular cytoskeleton, and in the mitotic spindle in both life cycle forms, and it likely serves multiple functions for these parasites. To begin to deconvolve the functions of KHARON, we have investigated partners associated with this protein and their roles in parasite biology. One KHARON associated protein, TbKHAP1, is a close interaction partner that can be crosslinked to KHARON by formaldehyde and pulled down in a molecular complex, and it colocalizes with TbKHARON in the basal body at the base of the flagellum. Knockdown of TbKHAP1 mRNA has similar phenotypes to knockdown of its partner TbKHARON, impairing trafficking of the Ca2+ channel to the flagellar membrane and blocking cytokinesis, implying that the TbKHARON/TbKHAP1 complex mediates trafficking of flagellar membrane proteins. Two other KHAPs, TbKHAP2 and TbKHAP3, are in close proximity to TbKHARON, but knockdown of their mRNAs does not affect trafficking of the Ca2+ channel. Two different flagellar membrane proteins, which are extruded from the flagellar membrane into extracellular vesicles, are also dependent upon TbKHARON for flagellar trafficking. These studies confirm that TbKHARON acts in complexes with other proteins to carry out various biological functions, and that some partners are involved in the core activity of targeting membrane proteins to the flagellum.

scholarly journals MexAB-OprM Efflux Pump Interaction with the Peptidoglycan of Escherichia coli and Pseudomonas aeruginosa

2021 ◽  
Vol 22 (10) ◽  
pp. 5328
Author(s):  
Miao Ma ◽  
Margaux Lustig ◽  
Michèle Salem ◽  
Dominique Mengin-Lecreulx ◽  
Gilles Phan ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Pseudomonas Aeruginosa ◽  
Cell Division ◽  
Membrane Proteins ◽  
Outer Membrane ◽  
Efflux Pump ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Active Efflux

One of the major families of membrane proteins found in prokaryote genome corresponds to the transporters. Among them, the resistance-nodulation-cell division (RND) transporters are highly studied, as being responsible for one of the most problematic mechanisms used by bacteria to resist to antibiotics, i.e., the active efflux of drugs. In Gram-negative bacteria, these proteins are inserted in the inner membrane and form a tripartite assembly with an outer membrane factor and a periplasmic linker in order to cross the two membranes to expulse molecules outside of the cell. A lot of information has been collected to understand the functional mechanism of these pumps, especially with AcrAB-TolC from Escherichia coli, but one missing piece from all the suggested models is the role of peptidoglycan in the assembly. Here, by pull-down experiments with purified peptidoglycans, we precise the MexAB-OprM interaction with the peptidoglycan from Escherichia coli and Pseudomonas aeruginosa, highlighting a role of the peptidoglycan in stabilizing the MexA-OprM complex and also differences between the two Gram-negative bacteria peptidoglycans.

Flagellar Membrane Proteins of Tetraselmis striata Butcher (Chlorophyta)

Protist ◽  
2000 ◽  
Vol 151 (2) ◽  
pp. 147-159 ◽  
Author(s):  
Stefan Gödel ◽  
Burkhard Becker ◽  
Michael Melkonian
Keyword(s):  
Membrane Proteins ◽  
Flagellar Membrane ◽  
Tetraselmis Striata

scholarly journals Divisome under Construction: Distinct Domains of the Small Membrane Protein FtsB Are Necessary for Interaction with Multiple Cell Division Proteins

2009 ◽  
Vol 191 (8) ◽  
pp. 2815-2825 ◽  
Author(s):  
Mark D. Gonzalez ◽  
Jon Beckwith
Keyword(s):  
Cell Division ◽  
Membrane Proteins ◽  
Protein Interactions ◽  
Cell Envelope ◽  
Coiled Coil ◽  
Main Function ◽  
Protein Protein Interactions ◽  
Molecular Scaffold ◽  
C Terminus ◽  
Under Construction

ABSTRACT Cell division in bacteria requires the coordinated action of a set of proteins, the divisome, for proper constriction of the cell envelope. Multiple protein-protein interactions are required for assembly of a stable divisome. Within the Escherichia coli divisome is a conserved subcomplex of inner membrane proteins, the FtsB/FtsL/FtsQ complex, which is necessary for linking the upstream division proteins, which are predominantly cytoplasmic, with the downstream division proteins, which are predominantly periplasmic. FtsB and FtsL are small bitopic membrane proteins with predicted coiled-coil motifs, which themselves form a stable subcomplex that can recruit downstream division proteins independently of FtsQ; however, the details of how FtsB and FtsL interact together and with other proteins remain to be characterized. Despite the small size of FtsB, we identified separate interaction domains of FtsB that are required for interaction with FtsL and FtsQ. The N-terminal half of FtsB is necessary for interaction with FtsL and sufficient, when in complex with FtsL, for recruitment of downstream division proteins, while a portion of the FtsB C terminus is necessary for interaction with FtsQ. These properties of FtsB support the proposal that its main function is as part of a molecular scaffold to allow for proper formation of the divisome.

scholarly journals Interaction Network among Escherichia coli Membrane Proteins Involved in Cell Division as Revealed by Bacterial Two-Hybrid Analysis

2005 ◽  
Vol 187 (7) ◽  
pp. 2233-2243 ◽  
Author(s):  
Gouzel Karimova ◽  
Nathalie Dautin ◽  
Daniel Ladant
Keyword(s):  
Escherichia Coli ◽  
Cell Division ◽  
Membrane Proteins ◽  
Hybrid System ◽  
Molecular Interactions ◽  
Interaction Network ◽  
Deletion Mapping ◽  
Division Site ◽  
Cooperative Association ◽  
Two Hybrid

ABSTRACT Formation of the Escherichia coli division septum is catalyzed by a number of essential proteins (named Fts) that assemble into a ring-like structure at the future division site. Several of these Fts proteins are intrinsic transmembrane proteins whose functions are largely unknown. Although these proteins appear to be recruited to the division site in a hierarchical order, the molecular interactions underlying the assembly of the cell division machinery remain mostly unspecified. In the present study, we used a bacterial two-hybrid system based on interaction-mediated reconstitution of a cyclic AMP (cAMP) signaling cascade to unravel the molecular basis of septum assembly by analyzing the protein interaction network among E. coli cell division proteins. Our results indicate that the Fts proteins are connected to one another through multiple interactions. A deletion mapping analysis carried out with two of these proteins, FtsQ and FtsI, revealed that different regions of the polypeptides are involved in their associations with their partners. Furthermore, we showed that the association between two Fts hybrid proteins could be modulated by the coexpression of a third Fts partner. Altogether, these data suggest that the cell division machinery assembly is driven by the cooperative association among the different Fts proteins to form a dynamic multiprotein structure at the septum site. In addition, our study shows that the cAMP-based two-hybrid system is particularly appropriate for analyzing molecular interactions between membrane proteins.

scholarly journals Dynamic interplay of ParA with the polarity protein, Scy, coordinates the growth with chromosome segregation in Streptomyces coelicolor

Open Biology ◽  
2013 ◽  
Vol 3 (3) ◽  
pp. 130006 ◽  
Author(s):  
Bartosz Ditkowski ◽  
Neil Holmes ◽  
Joanna Rydzak ◽  
Magdalena Donczew ◽  
Martyna Bezulska ◽  
...  
Keyword(s):  
Cell Division ◽  
Chromosome Segregation ◽  
Tip Growth ◽  
Streptomyces Coelicolor ◽  
Proximal Region ◽  
Cytoskeletal Protein ◽  
Mutant Form ◽  
Bacterial Cell Division ◽  
Aerial Hyphae ◽  
Dynamic Interplay

Prior to bacterial cell division, the ATP-dependent polymerization of the cytoskeletal protein, ParA, positions the newly replicated origin-proximal region of the chromosome by interacting with ParB complexes assembled on parS sites located close to the origin. During the formation of unigenomic spores from multi-genomic aerial hyphae compartments of Streptomyces coelicolor , ParA is developmentally triggered to form filaments along the hyphae; this promotes the accurate and synchronized segregation of tens of chromosomes into prespore compartments. Here, we show that in addition to being a segregation protein, ParA also interacts with the polarity protein, Scy, which is a component of the tip-organizing centre that controls tip growth. Scy recruits ParA to the hyphal tips and regulates ParA polymerization. These results are supported by the phenotype of a strain with a mutant form of ParA that uncouples ParA polymerization from Scy. We suggest that the ParA–Scy interaction coordinates the transition from hyphal elongation to sporulation.

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