Structural highlights
Function
[MSPA_MYCS2] The major porin in this organism, forms a water-filled channel which favors the permeation of cations, amino acids, iron Fe(3+) and less efficiently phosphate. Does not transport Fe-ExoMS, the predominant siderophore. Plays a role in transport of beta-lactamase and hydrophilic fluoroquinolone antibiotics such as norfloxacin as well as chloramphenicol. There are about 2400 porins in wild-type, 800 in an mspA deletion and 150 in a double mspA-mspC deletion. Different conductance values with maxima at 2.3 and 4.6 nanosiemens might be caused by a simultaneous reconstitution of MspA channels into the membrane or by the existence of different MspA conformations.[1] [2] [3] [4] [5]
Evolutionary Conservation
Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf.
Publication Abstract from PubMed
Mycobacteria have low-permeability outer membranes that render them resistant to most antibiotics. Hydrophilic nutrients can enter by way of transmembrane-channel proteins called porins. An x-ray analysis of the main porin from Mycobacterium smegmatis, MspA, revealed a homooctameric goblet-like conformation with a single central channel. This is the first structure of a mycobacterial outer-membrane protein. No structure-related protein was found in the Protein Data Bank. MspA contains two consecutive beta barrels with nonpolar outer surfaces that form a ribbon around the porin, which is too narrow to fit the thickness of the mycobacterial outer membrane in contemporary models.
The structure of a mycobacterial outer-membrane channel.,Faller M, Niederweis M, Schulz GE Science. 2004 Feb 20;303(5661):1189-92. PMID:14976314[6]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
See Also
References
- ↑ Niederweis M, Ehrt S, Heinz C, Klocker U, Karosi S, Swiderek KM, Riley LW, Benz R. Cloning of the mspA gene encoding a porin from Mycobacterium smegmatis. Mol Microbiol. 1999 Sep;33(5):933-45. PMID:10476028
- ↑ Stephan J, Bender J, Wolschendorf F, Hoffmann C, Roth E, Mailander C, Engelhardt H, Niederweis M. The growth rate of Mycobacterium smegmatis depends on sufficient porin-mediated influx of nutrients. Mol Microbiol. 2005 Nov;58(3):714-30. PMID:16238622 doi:http://dx.doi.org/10.1111/j.1365-2958.2005.04878.x
- ↑ Wolschendorf F, Mahfoud M, Niederweis M. Porins are required for uptake of phosphates by Mycobacterium smegmatis. J Bacteriol. 2007 Mar;189(6):2435-42. Epub 2007 Jan 5. PMID:17209034 doi:http://dx.doi.org/10.1128/JB.01600-06
- ↑ Danilchanka O, Pavlenok M, Niederweis M. Role of porins for uptake of antibiotics by Mycobacterium smegmatis. Antimicrob Agents Chemother. 2008 Sep;52(9):3127-34. doi: 10.1128/AAC.00239-08., Epub 2008 Jun 16. PMID:18559650 doi:http://dx.doi.org/10.1128/AAC.00239-08
- ↑ Jones CM, Niederweis M. Role of porins in iron uptake by Mycobacterium smegmatis. J Bacteriol. 2010 Dec;192(24):6411-7. doi: 10.1128/JB.00986-10. Epub 2010 Oct 15. PMID:20952578 doi:http://dx.doi.org/10.1128/JB.00986-10
- ↑ Faller M, Niederweis M, Schulz GE. The structure of a mycobacterial outer-membrane channel. Science. 2004 Feb 20;303(5661):1189-92. PMID:14976314 doi:10.1126/science.1094114
