Substrate-induced Conformational Changes in the Essential Peripheral Membrane-associated Mannosyltransferase PimA from Mycobacteria
Autor: | Mary Jackson, Pedro M. Alzari, David Giganti, Marcelo E. Guerin, Jana Korduláková, Mark J. van der Woerd, Francis Schaeffer, Alain Chaffotte, Petra Gest |
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Rok vydání: | 2009 |
Předmět: |
0303 health sciences
Conformational change Mannosyltransferase endocrine system diseases biology Stereochemistry Chemistry 030302 biochemistry & molecular biology Mutagenesis nutritional and metabolic diseases Substrate (chemistry) Cell Biology Biochemistry Cell membrane 03 medical and health sciences chemistry.chemical_compound medicine.anatomical_structure Guanosine diphosphate Glycosyltransferase biology.protein medicine Binding site Molecular Biology 030304 developmental biology |
Zdroj: | Journal of Biological Chemistry. 284:21613-21625 |
ISSN: | 0021-9258 |
DOI: | 10.1074/jbc.m109.003947 |
Popis: | Phosphatidyl-myo-inositol mannosyltransferase A (PimA) is an essential glycosyltransferase (GT) involved in the biosynthesis of phosphatidyl-myo-inositol mannosides (PIMs), which are key components of the mycobacterial cell envelope. PimA is the paradigm of a large family of peripheral membrane-binding GTs for which the molecular mechanism of substrate/membrane recognition and catalysis is still unknown. Strong evidence is provided showing that PimA undergoes significant conformational changes upon substrate binding. Specifically, the binding of the donor GDP-Man triggered an important interdomain rearrangement that stabilized the enzyme and generated the binding site for the acceptor substrate, phosphatidyl-myo-inositol (PI). The interaction of PimA with the β-phosphate of GDP-Man was essential for this conformational change to occur. In contrast, binding of PI had the opposite effect, inducing the formation of a more relaxed complex with PimA. Interestingly, GDP-Man stabilized and PI destabilized PimA by a similar enthalpic amount, suggesting that they formed or disrupted an equivalent number of interactions within the PimA complexes. Furthermore, molecular docking and site-directed mutagenesis experiments provided novel insights into the architecture of the myo-inositol 1-phosphate binding site and the involvement of an essential amphiphatic α-helix in membrane binding. Altogether, our experimental data support a model wherein the flexibility and conformational transitions confer the adaptability of PimA to the donor and acceptor substrates, which seems to be of importance during catalysis. The proposed mechanism has implications for the comprehension of the peripheral membrane-binding GTs at the molecular level. |
Databáze: | OpenAIRE |
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