Cytosolic Reactions During the Export of GspB Adhesin from <i>Streptococcus gordonii</i> (IMAGE)
Caption
Pathogenic gram-positive bacteria, such as S. gordonii, export a serine-rich adhesin to facilitate their attachment to host cells. Adhesin uses a dedicated secretion pathway, with several steps occurring in the cytosol before its translocation across the membrane. The adhesin GspB (shown in red) is first modified by N-acetylglucosamine (orange hexagon) and glucose (wheat hexagon) in a strictly sequential order. It is then targeted to the membrane by a complex of three accessory secretion proteins (Asp 1-3; shown in green, blue, and pink), two of which resemble carbohydrate-binding proteins (crystals structures are shown ribbon diagrams imbedded in space-filling presentation). Finally, GspB adhesin is moved through the membrane by a dedicated ATPase (SecA2) and membrane channel (SecY2) (both shown in cyan).
Credit
Yu Chen, Harvard Medical School
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