Whiteley secrtetion - Bacterial protein secretion...

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Gram-negative - translocation past the cytoplasmic / periplasm / outer membrane Gram-positive - translocation cytoplasmic membrane / cell wall Bacterial protein secretion
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Gram-negative secretion Type I   -   ATP-binding cassette (ABC) transporter Type II - general pathway ( Sec-dependent ) - major secretory pathway Type III - contact-dependent translocation into eukaryotic cells Type IV - ( Sec-like dependent ) - translocation of DNA / protein complex Type V -   auto-transporter ( Sec-dependent ) - includes β -pore forming domain             ~ Tat - (twin arginine transport) - moves folded proteins across CM SRP-   ( signal recognition particle) ( Sec-dependent ) - used for CM proteins
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Gram-negative - Type I secretion (ABC secretion) Type I secreted proteins:  RTX toxin (repeat in toxin) E. coli hemolysin bacteriocins metalloproteases ATP ADP N C OM P CM accessory factor Properties: - ATP-binding cassette transporter (also in eukaryotes) - Single step traversal across CM and OM - Signal sequence at C-terminus - is not removed - ABC channel - 6-12 transmembrane helices - Accessory factor - bridges periplasmic space - Post-translationally coordinated synthesis-translocation protein - GGXGSD ABC transporter accessory factor (MFP) Genes fused or coordinately expressed on operon: Outer membrane transport may not be linked
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Gram-negative - Type II secretion N C SecB L SecY,E,G (www.genome.ad.jp/kegg/ pathway/map/map03090.html) Sec- dependent secretory pathway Two step process: Step 1 - Transfer across cytoplasmic membrane - Leader (signal) peptide (18-26 aa) - SecA - binds leader (L), inserts in CM channel (requires ATP) - SecB - cytosolic chaperone (keeps unfolded) - SecYEG - CM channel complex post-translational translocation signal peptidase leader peptide 1-5 7-15 3-7 N ++ hydrophobic C mature protein
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