ABCC1 p.Gly392Ala
| Predicted by SNAP2: | A: D (66%), C: D (85%), D: D (91%), E: D (91%), F: D (95%), H: D (91%), I: D (91%), K: D (95%), L: D (91%), M: D (91%), N: D (91%), P: D (95%), Q: D (85%), R: D (95%), S: D (75%), T: D (85%), V: D (85%), W: D (95%), Y: D (95%), |
| Predicted by PROVEAN: | A: D, C: D, D: D, E: D, F: D, H: D, I: D, K: D, L: D, M: D, N: D, P: D, Q: D, R: D, S: D, T: D, V: D, W: D, Y: D, |
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[hide] Single site mutations in the hetero-oligomeric Mrp... J Biol Chem. 2010 Oct 1;285(40):30942-50. Epub 2010 Jul 12. Morino M, Natsui S, Ono T, Swartz TH, Krulwich TA, Ito M
Single site mutations in the hetero-oligomeric Mrp antiporter from alkaliphilic Bacillus pseudofirmus OF4 that affect Na+/H+ antiport activity, sodium exclusion, individual Mrp protein levels, or Mrp complex formation.
J Biol Chem. 2010 Oct 1;285(40):30942-50. Epub 2010 Jul 12., [PMID:20624916]
Abstract [show]
Mrp systems are widely distributed and structurally complex cation/proton antiporters. Antiport activity requires hetero-oligomeric complexes of all six or seven hydrophobic Mrp proteins (MrpA-MrpG). Here, a panel of site-directed mutants in conserved or proposed motif residues was made in the Mrp Na(+)(Li(+))/H(+) antiporter from an alkaliphilic Bacillus. The mutant operons were expressed in antiporter-deficient Escherichia coli KNabc and assessed for antiport properties, support of sodium resistance, membrane levels of each Mrp protein, and presence of monomeric and dimeric Mrp complexes. Antiport did not depend on a VFF motif or a conserved tyrosine pair, but a role for a conserved histidine in a potential quinone binding site of MrpA was supported. The importance of several acidic residues for antiport was confirmed, and the importance of additional residues was demonstrated (e.g. three lysine residues conserved across MrpA, MrpD, and membrane-bound respiratory Complex I subunits (NuoL/M/N)). The results extended indications that MrpE is required for normal membrane levels of other Mrp proteins and for complex formation. Moreover, mutations in several other Mrp proteins lead to greatly reduced membrane levels of MrpE. Thus, changes in either of the two Mrp modules, MrpA-MrpD and MrpE-MrpG, influence the other. Two mutants, MrpB-P37G and MrpC-Q70A, showed a normal phenotype but lacked the MrpA-MrpG monomeric complex while retaining the dimeric hetero-oligomeric complex. Finally, MrpG-P81A and MrpG-P81G mutants exhibited no antiport activity but supported sodium resistance and a low [Na(+)](in). Such mutants could be used to screen hypothesized but uncharacterized sodium efflux functions of Mrp apart from Na(+) (Li(+))/H(+) antiport.
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No. Sentence Comment
185 MrpC-G82I and MrpA-G392R (Group 3) were the sites of the identified original mutations, which led to the non-alkaliphilic phenotype in B. halodurans C-125.
X
ABCC1 p.Gly392Ala 20624916:185:139
status: NEW190 Neither of the two glycines that were mutated in the original B. halodurans C-125 mutagenesis is crucial for antiport inasmuch as the MrpA-G392A and MrpC-G82P mutants of B. pseudofirmus OF4 yielded mutant Mrp systems with no functional phenotype of significance and only a partial reduction in the membrane levels of MrpC itself for the MrpC-G82P mutant (see Group 8).
X
ABCC1 p.Gly392Ala 20624916:190:139
status: NEW220 Group 8 contains the remaining mutations: MrpA-Y136A, MrpA-H230A, MrpA-W232A, MrpA- Y258A, MrpA-H345A, MrpA-G392A, MrpA-F405A, MrpB-H34A, MrpC-G82P, MrpD-F135A, MrpD-F136A, MrpD-F136E, MrpD-F136T, MrpD- W228A, MrpE-P114A, and MrpF- P28G.
X
ABCC1 p.Gly392Ala 20624916:220:108
status: NEW215 Group 8 contains the remaining mutations: MrpA-Y136A, MrpA-H230A, MrpA-W232A, MrpA-Y258A, MrpA-H345A, MrpA-G392A, MrpA-F405A, MrpB-H34A, MrpC-G82P, MrpD-F135A, MrpD-F136A, MrpD-F136E, MrpD-F136T, MrpD-W228A, MrpE-P114A, and MrpF-P28G.
X
ABCC1 p.Gly392Ala 20624916:215:107
status: NEW