PTS Mannose-Fructose-Sorbose Family
 | This article may be too technical for most readers to understand. (September 2016) |
The PTS Mannose-Fructose-Sorbose (Man) Family (TC# 4.A.6) is a group of multicomponent PTS systems that are involved in sugar uptake in bacteria. This transport process is dependent on several cytoplasmic phosphoryl transfer proteins - Enzyme I (I), HPr, Enzyme IIA (IIA), and Enzyme IIB (IIB) as well as the integral membrane sugar permease complex (IICD). It is not part of the PTS-AG or PTS-GFL superfamilies.
Distinguishing characteristics from other PTS porters
[edit]The Man Family is unique in several respects among other PTS porter families:
- It is the only PTS family in which members possess a IID protein;
- It is the only PTS family in which the IIB constituent is phosphorylated on a histidyl rather than a cysteyl residue;[1]
- Its porter members usually exhibit broad specificity for a range of sugars, rather than being specific for just one or a few sugars.
The mannose porter of Escherichia coli, for example, can transport and phosphorylate glucose, mannose, fructose, glucosamine, N-acetylglucosamine, and N-acteylmannosamine.[2]
Structure
[edit]The structure of the E. coli IIAMan domain has been shown to exhibit an α/β doubly wound superfold.[3] The IIB domain also exhibits an α/β doubly wound superfold, but it is very dissimilar from that of the IIA domain.[4] Instead, it has the same topology as phosphoglyceromutase (PGM). Since both proteins (IIBMan and PGM) catalyze phosphoryl transfer with a phosphohistidine intermediate, both proteins show a similar distribution of active site residues, and both exhibit similar structures, they are probably homologous.
IICMan of E. coli has been reported to have six transmembrane α-helical segments, while IIDMan was reported to have only one.[5][6] However, hydropathy plots show multiple peaks of hydropathy, rendering the experimental result, suggesting 1 TMS, questionable.[7] These two proteins together are required for transport, although IICMan is presumed to comprise all or most of the sugar transporting channel.
Transport reaction
[edit]The generalized reaction catalyzed by members of the Man Family is:
- Sugar (out) + PEP (in) → Sugar-P (in) + pyruvate (in)
References
[edit]- ^ Lengeler, Joseph W.; Drews, Gerhard; Schlegel, Hans G. (1999). Biology of Prokaryotes. Stuttgart, Germany: Blackwell Science. pp. 83–84. ISBN 978-0-632-05357-5.
- ^ Plumbridge, Jacqueline (Jan 1999). "Convergent pathways for utilization of the amino sugars N-acetylglucosamine, N-acetylmannosamine, and N-acetylneuraminic acid by Escherichia coli". Journal of Bacteriology. 181 (1): 47–54. doi:10.1128/JB.181.1.47-54.1999. PMC 103530. PMID 9864311.
- ^ Hu, Jun; Hu, Kaifeng; Williams, David C.; Komlosh, Michal E.; Cai, Mengli; Clore, G. Marius (2008-04-18). "Solution NMR Structures of Productive and Non-productive Complexes between the A and B Domains of the Cytoplasmic Subunit of the Mannose Transporter of the Escherichia coli Phosphotransferase System". Journal of Biological Chemistry. 283 (16): 11024–11037. doi:10.1074/jbc.M800312200. ISSN 0021-9258. PMC 2447639. PMID 18270202.
- ^ Orriss, George L.; Erni, Bernhard; Schirmer, Tilman (2003-04-11). "Crystal structure of the IIB(Sor) domain of the sorbose permease from Klebsiella pneumoniae solved to 1.75A resolution". Journal of Molecular Biology. 327 (5): 1111–1119. doi:10.1016/s0022-2836(03)00215-8. ISSN 0022-2836. PMID 12662934.
- ^ Liu, Xueli; Zeng, Jianwei; Huang, Kai; Wang, Jiawei (2019-06-17). "Structure of the mannose transporter of the bacterial phosphotransferase system". Cell Research. 29 (8): 680–682. doi:10.1038/s41422-019-0194-z. ISSN 1748-7838. PMC 6796895. PMID 31209249.
- ^ Huang, Kai; Zeng, Jianwei; Liu, Xueli; Jiang, Tianyu; Wang, Jiawei (2021-04-06). "Structure of the mannose phosphotransferase system (man-PTS) complexed with microcin E492, a pore-forming bacteriocin". Cell Discovery. 7 (1): 20. doi:10.1038/s41421-021-00253-6. ISSN 2056-5968. PMC 8021565. PMID 33820910.
- ^ Huber, F.; Erni, B. (1996-08-01). "Membrane topology of the mannose transporter of Escherichia coli K12". European Journal of Biochemistry. 239 (3): 810–817. doi:10.1111/j.1432-1033.1996.0810u.x. ISSN 0014-2956. PMID 8774730.
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