scholarly journals Coexpression of MmpS5 and MmpL5 Contributes to Both Efflux Transporter MmpL5 Trimerization and Drug Resistance in Mycobacterium tuberculosis

mSphere ◽  
2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Kentaro Yamamoto ◽  
Noboru Nakata ◽  
Tetsu Mukai ◽  
Ikuro Kawagishi ◽  
Manabu Ato
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Membrane Protein ◽  
Fusion Protein ◽  
Membrane Fusion ◽  
Single Molecule ◽  
Efflux Transporter ◽  
Inner Membrane ◽  
Content Type ◽  
Membrane Fusion Protein ◽  
Resistance Nodulation Division

ABSTRACT The increasing occurrence of multidrug-resistant Mycobacterium tuberculosis (Mtb) is a serious threat to global public health. Among the many mechanisms of drug resistance, only resistance-nodulation-division (RND)-type multidrug efflux systems can simultaneously render bacteria tolerant to numerous toxic compounds, including antibiotics. The elevated expression of RND-type xenobiotic efflux transporter complexes, which consist of an inner membrane transporter, membrane fusion protein, and outer membrane channel, plays a major role in multidrug resistance. Among the 14 mycobacterial membrane protein large (MmpL) proteins identified as inner membrane transporters of Mtb, MmpL5 is known to participate in the acquisition of resistance to bedaquiline and clofazimine. MmpL5 exports these drugs by forming a complex with the membrane fusion protein mycobacterial membrane protein small 5 (MmpS5). However, the role of MmpS5 in the efflux of antituberculous drugs by MmpL5 remains unclear. In this study, we focused on the in vivo dynamics of MmpL5 using green fluorescent protein (GFP). Single-molecule observations of MmpL5 showed substantial lateral displacements of MmpL5-GFP without the expression of MmpS5. Nondiffusing MmpL5-GFP foci typically showed three-step photobleaching, suggesting that MmpL5 formed a homotrimeric functional complex on the inner membrane in the presence of MmpS5. These results suggest that the expression of MmpS5 facilitates the assembly of monomeric MmpL5 into a homotrimer that is anchored to the inner membrane to transport various antimycobacterial drugs. IMPORTANCE It has been reported that mycobacterial membrane protein large 5 (MmpL5), a resistance-nodulation-division (RND)-type inner membrane transporter in Mycobacterium tuberculosis (Mtb), is involved in the transport of antimycobacterial drugs. However, the functional roles of the membrane fusion protein mycobacterial membrane protein small 5 (MmpS5), organized as an operon with MmpL5, are unclear. Via the single-molecule imaging of MmpL5, we uncovered the maintenance of the functional trimeric complex structure of MmpL5 in the presence of MmpS5. These findings demonstrate that the assembly mechanisms of mycobacterial RND efflux systems are the dynamically regulated process through interactions among the components. This represents the first report of the single-molecule observation of Mtb efflux transporters, which may enhance our understanding of innate antibiotic resistance.

scholarly journals Assembly and Channel Opening of Outer Membrane Protein in Tripartite Drug Efflux Pumps of Gram-negative Bacteria

2012 ◽  
Vol 287 (15) ◽  
pp. 11740-11750 ◽  
Author(s):  
Yongbin Xu ◽  
Arne Moeller ◽  
So-Young Jun ◽  
Minho Le ◽  
Bo-Young Yoon ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Fusion Protein ◽  
Membrane Fusion ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Membrane Fusion Protein ◽  
Docking Model ◽  
Channel Opening

Gram-negative bacteria are capable of expelling diverse xenobiotic substances from within the cell by use of three-component efflux pumps in which the energy-activated inner membrane transporter is connected to the outer membrane channel protein via the membrane fusion protein. In this work, we describe the crystal structure of the membrane fusion protein MexA from the Pseudomonas aeruginosa MexAB-OprM pump in the hexameric ring arrangement. Electron microscopy study on the chimeric complex of MexA and the outer membrane protein OprM reveals that MexA makes a tip-to-tip interaction with OprM, which suggests a docking model for MexA and OprM. This docking model agrees well with genetic results and depicts detailed interactions. Opening of the OprM channel is accompanied by the simultaneous exposure of a protein structure resembling a six-bladed cogwheel, which intermeshes with the complementary cogwheel structure in the MexA hexamer. Taken together, we suggest an assembly and channel opening model for the MexAB-OprM pump. This study provides a better understanding of multidrug resistance in Gram-negative bacteria.

scholarly journals Mitochondrial outer and inner membrane fusion requires a modified carrier protein

2009 ◽  
Vol 184 (4) ◽  
pp. 569-581 ◽  
Author(s):  
Suzanne Hoppins ◽  
Jennifer Horner ◽  
Cheng Song ◽  
J. Michael McCaffery ◽  
Jodi Nunnari
Keyword(s):  
Functional Analysis ◽  
Membrane Protein ◽  
Fusion Protein ◽  
Membrane Fusion ◽  
Outer Membrane Protein ◽  
Carrier Protein ◽  
Inner Membrane ◽  
The Third ◽  
Membrane Tethering ◽  
Related Proteins

In yeast, three proteins are essential for mitochondrial fusion. Fzo1 and Mgm1 are conserved guanosine triphosphatases that reside in the outer and inner membranes, respectively. At each membrane, these conserved proteins are required for the distinct steps of membrane tethering and lipid mixing. The third essential component is Ugo1, an outer membrane protein in the mitochondrial transport protein family. We show that Ugo1 is a modified member of this family, containing three transmembrane domains and existing as a dimer, a structure that is critical for the fusion function of Ugo1. Our functional analysis of Ugo1 indicates that it is required distinctly for both outer and inner membrane fusion after membrane tethering, indicating that it operates at the lipid-mixing step of fusion. This role is distinct from the fusion dynamin-related proteins and thus demonstrates that at each membrane, a single fusion protein is not sufficient to drive the lipid-mixing step, but instead, this step requires a more complex assembly of proteins.

scholarly journals Mechanisms of Membrane Remodelling Mediated by Short Form of the Mitochondrial Inner Membrane Fusion Protein OPA1

2018 ◽  
Vol 114 (3) ◽  
pp. 615a
Author(s):  
Danyang Zhang ◽  
Yan Zhang ◽  
Tongxin Niu ◽  
Edward H. Egelman ◽  
Fei Sun
Keyword(s):  
Fusion Protein ◽  
Membrane Fusion ◽  
Short Form ◽  
Inner Membrane ◽  
Membrane Fusion Protein ◽  
Mitochondrial Inner Membrane

scholarly journals A membrane fusion protein, Ykt6, regulates epithelial cell migration via microRNA-mediated suppression of Junctional Adhesion Molecule A

Cell Cycle ◽  
2018 ◽  
Vol 17 (14) ◽  
pp. 1812-1831 ◽  
Author(s):  
Nayden G. Naydenov ◽  
Supriya Joshi ◽  
Alex Feygin ◽  
Siddharth Saini ◽  
Larisa Litovchick ◽  
...  
Keyword(s):  
Cell Migration ◽  
Epithelial Cell ◽  
Fusion Protein ◽  
Membrane Fusion ◽  
Adhesion Molecule ◽  
Membrane Fusion Protein ◽  
Epithelial Cell Migration
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