Study On The Role Of Cyo In Regulation Of Alkane Degradation Pathways In Alcanivorax Dieselolei

So far,with the increasingly serious problem of marine oil pollution,the research on the degradation mechanism of marine petroleum hydrocarbons has attracted much attention.Our laboratory gained novel insight into the mechanisms associated with alkane degradation in Alcanivorax dieselolei and key factors involved in alkane sensing,chemotaxis,uptake and regulation were identified in A.dieselolei B5 strain.In this report,we found that the Cyo terminal oxidase is situated between the chemotaxis and metabolism pathways and controls the expression of regulator genes associated with different alkane utilization pathways.Disruption of cyo D significantly decreased growth of the B5 strain on C28–C36 alkanes and on pristane but increased growth on C8–C24 alkanes compared with the wild-type B5 strain.Moreover Cyo downregulated the expression of alm R.However,the exact underlying mechanism remains unknown.Two gene,B5₀0995 and B5₀0996,which might code Two-Component Systems?TCS?by Gene Annotation were found downstream of cyo gene.And the B5₀0996 gene can regulate downstream alkane-degrading gene,which was verified.I made a secondary structure prediction about B5₀0995 coded protein,and demonstrated that it's C-terminal comprised histidine kinases domain and phosphoacceptor domain.There was Six transmembrane-spanning domain that anchor it to the bacterial membrane in N-terminal.In protein sequence alignment,there is a heptapeptide sequence of GGXXNPF that is 100% conserved pentapeptide ubiquinone binding motif.It is between the third and fourth transmembranes.The presence of oxidized ubiquinone inhibits the autophosphorylation activity of HK.This has been proved by an in vitro test.Investigation results show that Cyo oxidize reduced ubiquinol into oxidized ubiquinol in the respiratory chain,then oxidized form binds to HK and autophosphorylation occurs at HK's histidine residue,delivering phosphate group to RR,afterwards regulating alkane-degradation gene.