A Critical Alteration in Enolase is Identified in One Isolate of <i>Staphylococcus aureus</i> to Avoid Host Immunity

The ability of Staphylococcus aureus enolase to cleave plasminogen has been thought to be important for bacterial virulence. The genetic variants of Eno gene sequences were investigated in the present study to assess the pattern of biological diversity of one isolate of S. aureus isolated from patients with diabetic food from Iraqi hospitals. The observed variant’s possible impact in altering the enolase’s binding with its receptor was assessed by docking with plasminogen before and after mutation. Within the locus 791st, two variations were identified with two different consequences since A>T791 (in S2, S3, S14, and S17) and A>C791 (in S8) had given one nonsense (p.268Kter) and one missense (p.K>Q268) variants. Furthermore, two variations were also identified in the 791st locus with two different consequences since T>G947 (in S2, S3, S17) and T>C947 (in S8) had given one missense (p.L>V320) and one silent (T>C947) variant. It was inferred from the tree that our investigated samples were positioned in two phylogenetic positions within the S. aureus sequences with a noticeable tilt from the nearest strains. While the majority of samples occupied one phylogenetic position, the mutant samples were positioned in another distant position. Docking of the S8-based enolase variant with plasminogen showed a critical alteration in the binding of both proteins compared with the wild-type interactions. Based on the identified p.K>Q268 variant, the main mechanism through which the mutant S8 variant develops to interact with the host immunity is explained. The isolates were named as S8 (Δeno1G), S2 (Δeno1L), and S5(WT).