Streptococcus　pyogenes　(group　A　Streptococcus,　GAS)　has　caused　a　wide　variety　of　human　diseases.　Its　multifunctional　surface　dehydrogenase　(SDH)　is　crucial　for　GAS　life　cycle.　Furthermore,　GAS　infection　into　human　pharyngeal　cells　has　been　previously　shown　to　be　mediated　by　the　interaction　between　SDH　and　host　urokinase-type　plasminogen　activator　receptor　(uPAR).　However,　the　structural　information　of　SDH　remains　to　be　elucidated　and　there　are　few　detailed　studies　to　characterize　its　interaction　with　uPAR.　In-depth　research　on　these　issues　will　provide　potential　targets　and　strategies　for　combating　GAS.　Here,　we　prepared　recombinant　SDH　tetramer　in　Escherichia　coli　BL21　(DE3)　cells.　After　purification　and　crystallization,　we　determined　its　crystal　structure　at　1.74　angstrom.　The　unique　characteristics　might　be　potentially　explored　as　drug　targets　or　vaccine　immunogen.　We　subsequently　performed　gel　filtration　chromatography,　native-polyacrylamide　gel　electrophoresis　(PAGE)　and　in　vitro　pull-down　analyses.　The　results　showed　that　their　interaction　was　too　weak　to　form　stable　complexes　and　the　role　of　uPAR　involved　in　GAS　infection　needs　further　demonstration.　Altogether　the　current　work　provides　the　first　view　of　SDH　and　deepens　the　knowledge　of　GAS　infection.　(C)　2019　Elsevier　Inc.　All　rights　reserved.