Proper localization of proteins is crucial for all cells. The signal recognition particle (SRP) and its receptor (SR) constitute the major cellular machinery that mediates the co-translational targeting of roughly one third of cellular proteins to the eukaryotic endoplasmic reticulum, or the bacterial plasma membrane. Although rapid progress has been made in understanding the SRP pathway, many fundamental aspects of its molecular mechanism remain to be elucidated. Our general goal is to decipher, at a biochemical and biophysical level, the intricate inner workings of this universally conserved targeting machine. Our specific goal is to decipher the molecular mechanisms by which the loading of the cargo proteins on the SRP is coupled to its rapid delivery and efficient unloading to the translocation machinery, and to begin understand the mechanism of SRP in the context of the crowded environment at the ribosome exit site. To this end, three aims are envisioned: (1) We will decipher the role of the SRP RNA in mediating the communication between the cargo and the SRP and SR GTPases;(2) We will elucidate the precise mechanisms by which the cargo protein is transferred from the targeting to the translocation machinery;and (3) We will decipher whether and how the major co-translational chaperone, trigger factor, modulates the efficiency and fidelity of the SRP pathway. Ultimately, these studies will not only advance our understanding of the process of protein localization within the cell, but also provide new insights into the general principles of molecular recognition and regulation at a fundamental level. The proposed research is of a most basic nature, and will contribute profoundly to our general understanding of physiology and pathology of all living cells at the molecular level.

Public Health Relevance

Proper localization of proteins is essential for all cells. Mislocalization of proteins cause impaired cell growth, function, and eventually cell death, leading to devastating diseases such as cystic fibrosis, diabetes, and neurodegeneration. The proposed studies will significantly advance our understanding of the mechanism of membrane protein localization and biogenesis within the cell, and contribute profoundly to our general understanding of physiology and pathology of all living cells at a molecular level.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM078024-07
Application #
8529553
Study Section
Membrane Biology and Protein Processing (MBPP)
Program Officer
Ainsztein, Alexandra M
Project Start
2007-09-28
Project End
2016-08-31
Budget Start
2013-09-01
Budget End
2014-08-31
Support Year
7
Fiscal Year
2013
Total Cost
$334,292
Indirect Cost
$125,744
Name
California Institute of Technology
Department
None
Type
Schools of Engineering
DUNS #
009584210
City
Pasadena
State
CA
Country
United States
Zip Code
91125
Saraogi, Ishu; Shan, Shu-ou (2014) Co-translational protein targeting to the bacterial membrane. Biochim Biophys Acta 1843:1433-41
Saraogi, Ishu; Akopian, David; Shan, Shu-Ou (2014) Regulation of cargo recognition, commitment, and unloading drives cotranslational protein targeting. J Cell Biol 205:693-706
Guo, Huan; Xiong, Yi; Witkowski, Piotr et al. (2014) Inefficient translocation of preproinsulin contributes to pancreatic ? cell failure and late-onset diabetes. J Biol Chem 289:16290-302
von Loeffelholz, Ottilie; Knoops, Kevin; Ariosa, Aileen et al. (2013) Structural basis of signal sequence surveillance and selection by the SRP-FtsY complex. Nat Struct Mol Biol 20:604-10
Akopian, David; Shen, Kuang; Zhang, Xin et al. (2013) Signal recognition particle: an essential protein-targeting machine. Annu Rev Biochem 82:693-721
Voigts-Hoffmann, Felix; Schmitz, Nikolaus; Shen, Kuang et al. (2013) The structural basis of FtsY recruitment and GTPase activation by SRP RNA. Mol Cell 52:643-54
Akopian, David; Dalal, Kush; Shen, Kuang et al. (2013) SecYEG activates GTPases to drive the completion of cotranslational protein targeting. J Cell Biol 200:397-405
Ariosa, Aileen R; Duncan, Stacy S; Saraogi, Ishu et al. (2013) Fingerloop activates cargo delivery and unloading during cotranslational protein targeting. Mol Biol Cell 24:63-73
Zhang, Dawei; Sweredoski, Michael J; Graham, Robert L J et al. (2012) Novel proteomic tools reveal essential roles of SRP and importance of proper membrane protein biogenesis. Mol Cell Proteomics 11:M111.011585
Zhang, Dawei; Shan, Shu-ou (2012) Translation elongation regulates substrate selection by the signal recognition particle. J Biol Chem 287:7652-60

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