title: Bilobed shape of PadA reveals the connectivity from single to multi-domain bacterial plasminogen activators.
abstract: The bacterial plasminogen activator, PadA activates bovine, ovine and caprine plasminogen but remains inert toward human plasminogen. It shows high sequence homology with human plasminogen activator, staphylokinase (SAK) but generates active-site in bovine plasminogen non-proteolytically, similar to streptokinase (SK). To examine the structural requirements for the function of this unique cofactor, attempts were made to visualize solution structure of the PadA using small-angle X-ray scattering (SAXS) data and compare its shape profile with structural models based on crystal structures of staphylokinase and streptokinase domains. The bilobal shape solved for the PadA matched closely with the structural model of α-domain of SK rather than its sequence homolog, SAK. The SAXS based solution structure of the PadA exhibited an extra volume and high mobility around Y(90)DKAEK(95) and P(104)ITES(108) loop regions that were found to play a crucial role in its cofactor function. Structure and sequence analysis of bacterial cofactors and mammalian plasminogens displayed evolutionary conservation of crucial complimentary amino acids required for making a functional binary activator complex between bacterial plasminogen activators and their cognate partner plasminogen. These studies highlighted the importance of structure-function related evolutionary strategies adopted by bacteria for exploiting mammalian plasminogen activation system and its understanding may help in designing and the development of new thrombolytic agents for clinical interventions.
authors.affiliation: CSIR-Institute of Microbial Technology, Sector 39A, Chandigarh 160036, India.
authors.forename: Satish
authors.initials: S
authors.lastname: Singh
authors.affiliation: CSIR-Institute of Microbial Technology, Sector 39A, Chandigarh 160036, India.
authors.forename: Yogendra Singh
authors.initials: YS
authors.lastname: Rathore
authors.affiliation: CSIR-Institute of Microbial Technology, Sector 39A, Chandigarh 160036, India.
authors.forename: Timsy
authors.initials: T
authors.lastname: Bhando
authors.affiliation: CSIR-Institute of Microbial Technology, Sector 39A, Chandigarh 160036, India.
authors.forename: Mangesh Dattu
authors.initials: MD
authors.lastname: Hade
authors.affiliation: CSIR-Institute of Microbial Technology, Sector 39A, Chandigarh 160036, India. Electronic address: ashgang@imtech.res.in.
authors.lastname: Ashish
authors.affiliation: CSIR-Institute of Microbial Technology, Sector 39A, Chandigarh 160036, India. Electronic address: kanak@imtech.res.in.
authors.forename: Kanak L
authors.initials: KL
authors.lastname: Dikshit
mesh_terms: D000595:Amino Acid Sequence; D002850:Chromatography, Gel; D017124:Conserved Sequence; D019143:Evolution, Molecular; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010960:Plasminogen Activators / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D011487:Protein Conformation; D054730:Protein Interaction Domains and Motifs; D011994:Recombinant Proteins; D053838:Scattering, Small Angle; D016415:Sequence Alignment; D012996:Solutions; D013300:Streptokinase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
chemical_list: D011994:Recombinant Proteins; D012996:Solutions; D013300:Streptokinase; D010960:Plasminogen Activators
keywords: PadA; Plasminogen; Small angle X-ray scattering; Staphylokinase; Streptokinase