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 #
5R01GM078024-08
Application #
8731245
Study Section
Membrane Biology and Protein Processing Study Section (MBPP)
Program Officer
Ainsztein, Alexandra M
Project Start
2007-09-28
Project End
2016-08-31
Budget Start
2014-09-01
Budget End
2015-08-31
Support Year
8
Fiscal Year
2014
Total Cost
Indirect Cost
Name
California Institute of Technology
Department
Type
Biomed Engr/Col Engr/Engr Sta
DUNS #
City
Pasadena
State
CA
Country
United States
Zip Code
91125
Wang, Shuai; Yang, Chien-I; Shan, Shu-Ou (2017) SecA mediates cotranslational targeting and translocation of an inner membrane protein. J Cell Biol 216:3639-3653
Jomaa, Ahmad; Fu, Yu-Hsien Hwang; Boehringer, Daniel et al. (2017) Structure of the quaternary complex between SRP, SR, and translocon bound to the translating ribosome. Nat Commun 8:15470
Hwang Fu, Yu-Hsien; Huang, William Y C; Shen, Kuang et al. (2017) Two-step membrane binding by the bacterial SRP receptor enable efficient and accurate Co-translational protein targeting. Elife 6:
Chen, Yang; Shen, Kuang; Shan, Shu-Ou et al. (2016) Analyzing Single-Molecule Protein Transportation Experiments via Hierarchical Hidden Markov Models. J Am Stat Assoc 111:951-966
Shan, Shu-Ou (2016) ATPase and GTPase Tangos Drive Intracellular Protein Transport. Trends Biochem Sci 41:1050-1060
Ariosa, Aileen; Lee, Jae Ho; Wang, Shuai et al. (2015) Regulation by a chaperone improves substrate selectivity during cotranslational protein targeting. Proc Natl Acad Sci U S A 112:E3169-78
von Loeffelholz, Ottilie; Jiang, Qiyang; Ariosa, Aileen et al. (2015) Ribosome-SRP-FtsY cotranslational targeting complex in the closed state. Proc Natl Acad Sci U S A 112:3943-8
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
Saraogi, Ishu; Shan, Shu-ou (2014) Co-translational protein targeting to the bacterial membrane. Biochim Biophys Acta 1843:1433-41
Zhang, Xin; Shan, Shu-ou (2014) Fidelity of cotranslational protein targeting by the signal recognition particle. Annu Rev Biophys 43:381-408

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