ABCMdb

ABCC8 p.Ala146Val

Predicted by SNAP2:	C: N (78%), D: D (66%), E: D (66%), F: D (53%), G: N (82%), H: D (63%), I: N (61%), K: D (66%), L: N (87%), M: N (53%), N: N (72%), P: N (53%), Q: N (53%), R: N (57%), S: N (93%), T: N (87%), V: N (78%), W: D (71%), Y: D (59%),
Predicted by PROVEAN:	C: N, D: D, E: N, F: D, G: D, H: D, I: N, K: D, L: N, M: N, N: D, P: D, Q: N, R: D, S: N, T: N, V: N, W: D, Y: D,

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[hide] Study of the structure-activity relationships for ... Biochem J. 2001 Feb 1;353(Pt 3):453-8. Lemaitre N, Callebaut I, Frenois F, Jarlier V, Sougakoff W
Study of the structure-activity relationships for the pyrazinamidase (PncA) from Mycobacterium tuberculosis.
Biochem J. 2001 Feb 1;353(Pt 3):453-8., [PMID:11171040]

Abstract [show]
In an attempt to investigate the molecular basis of pyrazinamide hydrolysis by the PncA protein from Mycobacterium tuberculosis, we determined the pyrazinamidase activity of nine PncA mutants bearing a single amino acid substitution. Among them, three mutants (D8G, K96T and S104R) had virtually no activity (< or =0.004 unit/mg), five (F13S, T61P, P69L, Y103S and A146V) retained a low level of activity (0.06-0.25 unit/mg) and one (T167L) exhibited a wild-type activity (1.51 units/mg). The possible structural effects of these substitutions were assessed by analysing a three-dimensional model of the PncA protein constructed on the basis of the crystal structure of the N-carbamoylsarcosine amidohydrolase (CSHase) from Arthrobacter sp., an amidohydrolase which was found by hydrophobic cluster analysis to be closely related to PncA. In the PncA model, five of the mutated residues, Asp-8, Phe-13, Lys-96, Tyr-103 and Ser-104, were located within a 6 A sphere around the cysteine residue Cys-138, which could be the counterpart of the active cysteine residue Cys-177 found in the CSHase. Among the remaining mutated residues, Thr-61, Pro-69 and Ala-146 were found to be more distant from Cys-138 but were associated with structural elements contributing to the catalytic centre, whereas Thr-167 was situated in an alpha-helix located far from the putative active site. These data suggest that the decrease in pyrazinamidase activity observed in the PncA mutant proteins is well correlated with the structural modifications the mutations can cause in the environment of the putative active cysteine Cys-138.

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5 Among them, three mutants (D8G, K96T and S104R) had virtually no activity ( 0.004 unit\mg), five (F13S, T61P, P69L, Y103S and A146V) retained a low level of activity (0.06-0.25 unit\mg) and one (T167L) exhibited a wild-type activity (1.51 units\mg). Login to comment
58 All the mutants harboured a single amino acid substitution located either in the conserved (D8G, F13S, P69L, K96T, Y103S, S104R and A146V) or non-conserved (T61P and T167I) regions identified previously in the M. tuberculosis PncA protein [5]. Login to comment
66 The second group contained five mutants, F13S, Y103S, A146V, T61P and P69L, which retained a low level Table 1 PZase activities of wild-type (WT) and PncA mutant proteins AS, active site, defined by the residues located within a 6 A/ sphere from the putative active Cys-138 found at the centre of the catalytic cleft (shown in Figure 2). Login to comment
67 Strain Specific activity (units/mg of protein) Location of the mutated residue in the predicted PncA secondary structure PncA WT* 1.33 - PncA WT† 4.43 - K96T 0.002 β3 (AS) D8G 0.004 Loop connecting β1 and αC (AS) S104R 0.004 Loop connecting β3 and αD (AS) F13S 0.06 Loop connecting β1 and αC (AS) Y103S 0.11 Loop connecting β3 and αD (AS) A146V 0.17 αE T61P 0.21 Loop connecting β2 and β3 P69L 0.25 Loop connecting β2 and β3 T167I 1.51 αF * Reference strain H37Rv. Login to comment
109 The four remaining mutants, T61P, P69L, A146V and T167I, were characterized by the replacement of amino acid residues more distant from Cys-138, but three of them were altered in positions associated with structural elements contributing to the active site, i.e. Ala-146 in the αE helix (Figure 2D) and Thr-61 and Pro-69 in the long loop connecting strands β2 and β3 and holding Trp-68 (Figures 1A and 1B). Login to comment
119 The five mutants F13S, Y103S, A146V, T61P and P69L exhibited a significant decrease in PncA activity (see Table 1). Login to comment
129 The moderate level of activity (0.1-0.2 unit\mg) displayed by the three remaining mutants T61P, P69L and A146V seems to be correlated, in the putative PncA structure, to the location of the corresponding substituted amino acids, which are relatively distant from the active cysteine. Login to comment