Crystallography Studies Of The Substrate Binding Domain Of The ABC Transporter COG1732 From Mycobacterium Tuberculosis

ABC transporters are a class of ancient,widely present transmembrane transporters that appear in archaea,eubacteria and eukaryotes.The main function of this protein is through membrane transport of ATP-driven substances,which are typically composed of three domains,including transmembrane domain(TMDs),nucleic acid binding domains(NBDs)and substrate binding domains(SBDs).Mycobacterium tuberculosis is a highly pathogenic pathogen that causes tuberculosis.Its cell membrane has the common characteristics of Gram-positive and Gram-negative bacteria,which can proliferate in all organs of the body and most common in the lungs.Whereas ABC transporters mediate transport of substances may be an important mechanism for their adaptation to different host cell environments.This study was aimed at the biochemical function and three-dimensional structure of the substrate binding protein COG1732 of an ABC transporter in Mycobacterium tuberculosis.Sequence analysis showed that the protein had the 27.8% sequence-identical as that of the compatible solute-binding protein,suggesting that the protein may be related to the adaptation of Mycobacterium tuberculosis to the highly permeable environment,but we found that the protein was not bound by fluorescence quenching Betaine,choline and other compatible solute.Further screening by compounds We found a series of phenolic compounds 2`,6`-Dihydroxyacetophenone(2`,6`-HAP)、Monoacetylphloroglucinol(MAPG)、2`-Hydroxyacetophenone(2`-HAP)、4`-Hydroxyacetophenone(4`-HAP)、2`,4`-Dihydroxyacetophloroglucinol(DAPG)、Phloretin 、2`,4`-Dihydroxyacetophenone(2`,4`-HAP)that bind to COG1732,and the dissociation constants of these compounds with COG1732 bind between 20 um and 200 um.At the same time,we also tried to crystallize the COG1732,and obtained high quality protein crystals by optimizing the recombinant protein sequence,which laid a solid foundation for revealing the biochemical function of COG1732 and its structural biological basis of ligand molecules.