TY  - JOUR
ID  - open480
UR  - http://www.sciencedirect.com/science/article/pii/S1047847711000268
IS  - 2
A1  - Singh, Mirage
A1  - Kumar, Pankaj
A1  - Karthikeyan, Subramanian
N2  - 3,4-dihydroxy 2-butanone 4-phosphate synthase (DHBPS) and GTP cyclohydrolase-II (GTPCH-II) are the two initial enzymes involved in riboflavin biosynthesis pathway, which has been shown to be essential for the pathogens. In Mycobacterium tuberculosis (Mtb), the ribA2 gene (Rv1415) encodes for the bi-functional enzyme with DHBPS and GTPCH-II domains at N- and C-termini, respectively. We have determined three crystal structures of Mtb-DHBPS domain in complex with phosphate and glycerol at pH 6.0, with sulphate at pH 4.0 and with zinc and sulphate at pH 4.0 at 1.8, 2.06 and 2.06 Å resolution, respectively. The hydrodynamic volume and enzyme activity studies revealed that the Mtb-DHBPS domain forms a functional homo-dimer between the pH 6.0 and 9.0, however, at pH 5.0 and below, it forms a stable inactive monomer in solution. Furthermore, the functional activity of Mtb-DHBPS and its dimeric state could be restored by increasing the pH between 6.0 and 9.0. The comparison of crystal structures determined at different pH revealed that the overall three-dimensional structure of Mtb-DHBPS monomer remains the same. However, the length of the ?6-helix at pH 6.0 has increased from 15 to 22 Å in pH 4.0 by increasing the number of amino acids contributing to the ?6-helix from 11 to 15, achieving a higher structural stability at pH 4.0. Taken together our experiments strongly suggest that the Mtb-DHBPS domain can transit between inactive monomer to active dimer depending upon its pH values, both in solution as well in crystal structure.
VL  - 174
TI  - Structural basis for pH dependent monomer-dimer transition of 3,4-dihydroxy 2-butanone-4-phosphate synthase domain from Mycobacterium tuberculosis.
AV  - public
EP  - 84
N1  - Copyright of this article belongs to Elsevier Science
Y1  - 2011/05//
PB  - Elsevier Science
JF  - Journal of structural biology
KW  - Riboflavin; FMN/FAD; Antibacterial; Drug target; VitaminB2
SN  - 1095-8657
SP  - 374
ER  -