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Peter Chien

Assistant Professor

All biological systems rely on protein synthesis and degradation (proteolysis). Regulation of proteolysis is needed to ensure proper signaling and growth in all cell types. For example, cells limit DNA replication to specific phases of growth by rapidly degrading factors that trigger transitions between these phases. The improper degradation of these factors results in pathological conditions like cancer. In addition, chemical or environmental shocks can generate toxic, damaged proteins that must be eliminated before they can cause harm to the cell. The buildup of these types of damaged proteins is a hallmark of many neurological diseases such as Alzheimer's and Huntington's diseases, further illustrating the importance of properly regulating protein degradation.

Protein degradation is a double-edged sword. Since protein degradation is irreversible, unregulated proteolysis would rapidly destroy all the proteins in the cell. However, the cell must have a robust way to rapidly degrade those proteins that are unwanted. Therefore, regardless of the specific organism or system, there are fundamental questions common to all proteolysis pathways. How are certain proteins targeted for destruction while other proteins are not? How does the cell regulate proteolysis to maintain normal growth while responding to environmental changes?

Current Research
The general research objectives of my lab are to determine how proteolysis is regulated and the biological consequences of regulated proteolysis. We take an integrated approach to this question, using biochemical, structural, genetic and proteomic tools to address mechanistic and cellular questions. We are particularly interested in understanding how regulated protein degradation is used in bacteria. Protein degradation is crucial for bacteria development and virulence, and just as defects in proteolysis result in human disease, defects in proteolysis result in loss of bacterial fitness. This presents us with a timely opportunity to characterize specific bacterial pathways that rely on regulated proteolysis as targets for novel antibiotics that are sorely needed due to the recent alarming rise of multidrug-resistant bacteria.

Learn more at www.biochem.umass.edu/faculty/peter-chien

Academic Background

  • PhD University of California, San Francisco
  • Postdoctoral training: Massachusetts Institute of Technology
Liu J, Zeinert R, Francis L, Chien P. (2018) Lon recognition of the replication initiator DnaA requires a bipartite degron. Mol Microbiol. Oct 4. doi: 10.1111/mmi.14146.
Joshi KK, Battle CM, Chien P. (2018) The polar localization hub protein PopZ restrains adaptor dependent ClpXP proteolysis in Caulobacter crescentus. J Bacteriol. Aug 6.
Mahmoud S, Chien P. (2018) Regulated Proteolysis in Bacteria. Annu Rev in Biochem. 2018. Jun 20;87:677-696.
Liu J, Francis LI, Jonas K, Laub MT, Chien P. (2016) ClpAP is an auxiliary protease for DnaA degradation in Caulobacter crescentus. Mol Microbiol. 2016 Dec;102(6):1075-1085.
Joshi KK, Berge M, Radhakrishnan SK, Viollier PH, Chien P. (2015) An adaptor hierarchy regulates proteolysis during a bacterial cell cycle. Cell. Oct 8;163(2):419-31.
Lau J, Hernandez-Alicea L, Vass RH, Chien P. (2015). A phosphosignaling adaptor primes the AAA+ protease ClpXP to drive cell cycle regulated proteolysis. Molecular Cell. Jul 2;59(1):104-16. doi: 10.1016/j.molcel.2015.05.014.
Gora KG, Cantin A, Wohlever M, Joshi KK, Perchuk BS, Chien P, Laub MT. "Regulated proteolysis of a transcription factor complex is critical to cell cycle progression in Caulobacter crescentus". Molecular Microbiology. 2013 Mar;87(6):1277-89. Pubmed PMID: 23368090; PubMed Central PMCID: PMC3596498.
Bhat NH, Vass RH, Stoddard PR, Shin DK, Chien P. "Identification of ClpP substrates in Caulobacter crescentus reveals a role for regulated proteolysis in bacterial development". Molecular Microbiology. 2013 May 7. doi: 10.1111/mmi.12241. Pubmed PMID: 23647068; PubMed Central PMCID: PMC3681837.
Jonas K, Liu J, Chien P, Laub MT. "Proteotoxic stress induces a cell cycle arrest by stimulating Lon to degrade the replication initiator DnaA". Cell. 2013 August 1; 154: 623-636. doi: 10.1016/j.cell.2013.06.034. PubMed PMID: 23911325; PubMed Central PMCID: PMC3749246 *highlighted in Nature Reviews Microbiology 11, 660–661 (2013)
Vass, RH, Chien. P. "Critical clamp loader processing by an essential AAA+ protease in Caulobacter crescentus." Proc Natl Acad Sci USA. 2013 Nov 5;110(45):18138-43. doi: 10.1073/pnas.1311302110. Epub 2013 Oct 21. PubMed PMID: 24145408; PubMed Central PMCID: PMC3831445
Contact Info

Department of Biochemistry and Molecular Biology
Life Science Laboratories N325
240 Thatcher Way
Amherst, MA 01003-9292

(413) 545-2310