Comparative Structural and Functional Analysis of Staphylococcus aureus Glucokinase with other Bacterial Glucokinases

Glucokinase is classified in bacteria based upon having ATP binding site and ‘repressor/open reading frames of unknown function/sugar kinases’ motif, the sequence of glucokinase gene (JN645812) of Staphylococcus aureus ATCC12600 showed presence of ATP binding site and ‘repressor/open reading frames of unknown function/sugar kinases’ motif. We have earlier observed glucokinase of S. aureus has higher affinity towards the substrate compared to other bacterial glucokinase and under anaerobic condition with increased glucose concentration S. aureus exhibited higher rate of biofilm formation. To establish this, 3D structure of glucokinase was built using homology modeling method, the PROCHECK and ProSA-Web analysis indicated this built glucokinase structure was close to the crystal structure. This structure was superimposed with different bacterial glucokinase structures and from the root-mean-square deviation values, it is concluded that S. aureus glucokinase exhibited very close homology with Enterococcus faecalis and Clostridium difficle while with other bacteria it showed high degree of variations both in domain and nondomain regions. Glucose docking results indicated -12.3697 kcal/mol for S. aureus glucokinase compared with other bacterial glucokinase suggesting higher affinity of glucose which correlates with enzyme kinetics and higher rate of biofilm formation.