Process_ProteinTranslocation – Protein translocation

Name
WID Process_ProteinTranslocation
Name Protein translocation
 
Implementation
Initialization order 21 View in model
 
Reactions
Chemical reactions View in model
 
Parameters
Parameters View in model
 
Comments
Comments Introduction Protein transport systems transport up to 40% of proteins: 10% of B. subtilis proteins are secreted; 25-30% of proteins are membrane localized. Protein transport systems are classified into multiple types. Each type recognizes a distinct signal peptide, and uses a distinct machinery to transport proteins into and through the membrane. Type I transport systems (eg. TolC) recognize N-terminal sequences, and transport unfolded proteins post-translationally. Type II transport systems (eg. Sec) recognize N-terminal positively charged sequences and transport nascent proteins co-translationally. Type III systems (eg. TAT) recognize C-terminal sequences and transport folded proteins. M. genitalium possesses only a type II protein transport system. M. genitalium does not contain sortases or foldases. M. genitalium Type II Sec System M. genitalium possesses a type II protein transport system: Signal recognition particle (SRP) – GTP-bound form competes with trigger factor which recognizes less hydrophobic sequences to binds signal peptides co-translationally. Coordinates nascent peptides to the signal particle receptor. Recognizes a positively charged N-terminal sequence of 10-15 residues. SRP is a ribonucleoprotein consisting of 1 protein subunit (Ffh, MG_048) which contains a GTP binding domain and 1 4.5S RNA (scRNA, ffs, MG_0001) Signal recognition particle receptor (SR, FtsY, MG_297) – GTP-bound form binds signal recognition particle, thereby localizing the nascent peptide to the membrane. Hydrolysis of both GTPs bound to the receptor and to Ffh dissociates the peptide-SRP-SR complex, freeing the SRP, and shuttling a peptide-SR complex to the translocase [PUB_0010]. SecA translocase – Processively translocates the nascent polypeptide through the translocase pore via an ATP-dependent mechanism. SecA translocates 4-5 aa/ATP [PUB_0003] at a rate 270 pmol aa/min [PUB_0001]. SecYEGDF YjaC translocase pore – Forms a membrane pore through which unfolded proteins pass. Accessory proteins such as YjaC increase the efficiency of transport and are not essential. Integral membrane proteins begin folding by a phosphatidyl ethanolamine-dependent mechanism while translocating through the membrane. Membrane protein complexation occurs after membrane insertion. Type II signal peptidase – Extracellularly cleaves the signal peptide of lipoproteins at a lipobox (L[ASI][GA]C). Diacylglyceryl transferase – Transfers a N-terminal lipid anchor to lipoproteins after cleavage by the type II signal peptidase. Note_ProteinLocalization_SignalPeptides describes the curation of protein signal peptides. Simulation Translocates protein to and through membrane using signal recognition particle signal recognition particle receptor translocase ATPase translocase pore Cleaves signal peptides of, and transfers diacylglyceryl to lipoproteins using prolipoprotein signal peptidase II diacylgylceryl transferase References Ross E. Dalbey and Gunner von Heijne (2002). Protein targeting, transport, and translocation. Academic Press, San Diego. [PUB_0003] June R. Scott and Timothy C. Barnett (2006). Surface Proteins of Gram-Positive Bacteria and How They Get There. Annu Rev Microbiol. 60: 397-423. [PUB_0626] Christos Stathopoulos, Yihfen T. Yen, Casey Tsang and Todd Cameron (2008). Protein Secretion in Bacterial Cells. Bacterial Physiology. Springer Berlin: Heidelberg. [PUB_0627]. van Wely KH, Swaving J, Freudl R, Driessen AJ (2001). Translocation of proteins across the cell envelope of Gram-positive bacteria. FEMS Microbiol Rev. 25(4): 437-54.[PUB_0004] Hutchings MI, Palmer T, Harrington DJ, Sutcliffe IC (2009). Lipoprotein biogenesis in Gram-positive bacteria: knowing when to hold 'em, knowing when to fold 'em. Trends Microbiol. 17(1): 13-21. [PUB_0629] Bernstein HD (2000). The biogenesis and assembly of bacterial membrane proteins. Curr Opin Microbiol. 3(2): 203-9. [PUB_0635] Dowhan W, Bogdanov M (2009). Lipid-dependent membrane protein topogenesis. Annu Rev Biochem. 78: 515-40. [PUB_0636] Xie K, Dalbey RE (2008). Inserting proteins into the bacterial cytoplasmic membrane using the Sec and YidC translocases. Nat Rev Microbiol. 6(3): 234-44. [PUB_0018]
References
  1. Eds Dalbey RE, von Heijne G. Protein Targeting, Transport, and Translocation. Academic Press, San Diego (2002). WholeCell: PUB_0003, ISBN: 9780122007316

  2. Bernstein HD. The biogenesis and assembly of bacterial membrane proteins. Curr Opin Microbiol 3, 203-9 (2000). WholeCell: PUB_0635, PubMed: 10744997

  3. Dowhan W, Bogdanov M. Lipid-dependent membrane protein topogenesis. Annu Rev Biochem 78, 515-40 (2009). WholeCell: PUB_0636, PubMed: 19489728

  4. Hutchings MI, Palmer T, Harrington DJ, Sutcliffe IC. Lipoprotein biogenesis in Gram-positive bacteria: knowing when to hold 'em, knowing when to fold 'em. Trends Microbiol 17, 13-21 (2009). WholeCell: PUB_0629, PubMed: 19059780

  5. Peluso P, Shan SO, Nock S, Herschlag D, Walter P. Role of SRP RNA in the GTPase cycles of Ffh and FtsY. Biochemistry 40, 15224-33 (2001). WholeCell: PUB_0010, PubMed: 11735405

  6. ... 5 more

  7. Scott JR, Barnett TC. Surface proteins of gram-positive bacteria and how they get there. Annu Rev Microbiol 60, 397-423 (2006). WholeCell: PUB_0626, PubMed: 16753030

  8. Stathopoulos C, Yen YT, Tsang C, Cameron T. Eds El-Sharoud W. Protein Secretion in Bacterial Cells. Springer Berlin: Heidelberg 129-153 (2008). WholeCell: PUB_0627, ISBN: 9783540749219

  9. Tomkiewicz D, Nouwen N, van Leeuwen R, Tans S, Driessen AJ. SecA supports a constant rate of preprotein translocation. J Biol Chem 281, 15709-13 (2006). WholeCell: PUB_0001, PubMed: 16601117

  10. Xie K, Dalbey RE. Inserting proteins into the bacterial cytoplasmic membrane using the Sec and YidC translocases. Nat Rev Microbiol 6, 234-44 (2008). WholeCell: PUB_0018, PubMed: 18246081

  11. van Wely KH, Swaving J, Freudl R, Driessen AJ. Translocation of proteins across the cell envelope of Gram-positive bacteria. FEMS Microbiol Rev 25, 437-54 (2001). WholeCell: PUB_0004, PubMed: 11524133

 
Metadata
Created 2012-10-01 15:07:35
Last updated 2012-10-01 15:14:00