This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Part of my research focuses on a crucial RNA processing and degradation machinery, the exosome, which has often been called the proteasome for RNA. Initially identified from mutations causing 5.8S rRNA 3 end processing defects, the exosome is a conserved 300 - 400 kD 3 -to-5 exoribonuclease complex present in both the nucleus and the cytoplasm of eukaryotic cells. The exosome consists of a core of ten proteins: Rrp4p, Rrp40p to Rrp46p, Mtr3p, and Csl4p (yeast nomenclature), all are essential for cell viability. Six of them are phosphorolytic RNases; the other four are predicted to be hydrolytic RNases. In the nucleus, the exosome is required for the 3 end formation of 5.8S rRNA and the degradation of the 5 -external transcribed spacer; participated in the 3 end maturation of small nuclear and nucleolar RNAs; and involved in degradation of inefficiently spliced or hypoadenylated pre-mRNAs. The cytoplasmic exosome is involved in the degradation of mRNAs containing premature termination codons, lacking termination codons, or bearing AU-rich elements (AREs) near the 3 untranslated region. To gain insights into the architecture and enzymatic mechanism of the exosome, I have proposed to determine the crystal structures of the 300 kD, 4-preotein archaeal exosome, the 10-protein eukaryotic exosome, and the exosome-RNA substrate complexes. The long term goals include determination of exosome-adaptor protein complexes to investigate its regulation. Exciting progress has been made in expression, purification, and crystallization of the archaeal exosome complex. Well-behaving crystals diffracted X-ray to ~ 2.4 resolution at synchrotron radiation source. Additional beam time is needed to complete Se-MAD phasing and carry out structural enzymology studies on the archaeal exosome complex. The second part of my research focuses on Signal Recognition Particle (SRP) mediated co-translational translocation of proteins across or into membranes. This vital cellular process requires the translating ribosome to be membrane-targeted by the SRP, a ribonucleoprotein complex conserved in all three kingdoms of life. SRP recognizes the hydrophobic signal sequence of the nascent protein emerging from the ribosome, resulting in transient elongation arrest in eukaryotes, and targets the ribosome to the membrane via a GTP-dependent interaction with the SRP receptor (SR). The ribosome is then handed over to the translocon, where protein translation and translocation happens simultaneously. The SRP-SR dissociates following GTP hydrolysis and SRP cycle resumes. Crystals of the E. coli SRP bound to the receptor complex has been obtained and diffracted X-ray to medium resolution of 6 . Synchrotron radiation source is absolutely needed to screen for cryoprotection conditions and alternative crystal forms to determine the complex structure. Future research will also target the more complicated eukaryotic SRP complex to fully understand the role of RNA in the co-translational protein targeting process.

Agency
National Institute of Health (NIH)
Institute
National Center for Research Resources (NCRR)
Type
Biotechnology Resource Grants (P41)
Project #
5P41RR001646-24
Application #
7357741
Study Section
Special Emphasis Panel (ZRG1-BBCA (40))
Project Start
2006-07-01
Project End
2007-06-30
Budget Start
2006-07-01
Budget End
2007-06-30
Support Year
24
Fiscal Year
2006
Total Cost
$51,950
Indirect Cost
Name
Cornell University
Department
Physics
Type
Schools of Arts and Sciences
DUNS #
872612445
City
Ithaca
State
NY
Country
United States
Zip Code
14850
Kozlov, Guennadi; Wong, Kathy; Gehring, Kalle (2018) Crystal structure of the Legionella effector Lem22. Proteins 86:263-267
Ménade, Marie; Kozlov, Guennadi; Trempe, Jean-François et al. (2018) Structures of ubiquitin-like (Ubl) and Hsp90-like domains of sacsin provide insight into pathological mutations. J Biol Chem 293:12832-12842
Xu, Jie; Kozlov, Guennadi; McPherson, Peter S et al. (2018) A PH-like domain of the Rab12 guanine nucleotide exchange factor DENND3 binds actin and is required for autophagy. J Biol Chem 293:4566-4574
Dean, Dexter N; Rana, Pratip; Campbell, Ryan P et al. (2018) Propagation of an A? Dodecamer Strain Involves a Three-Step Mechanism and a Key Intermediate. Biophys J 114:539-549
Chen, Yu Seby; Kozlov, Guennadi; Fakih, Rayan et al. (2018) The cyclic nucleotide-binding homology domain of the integral membrane protein CNNM mediates dimerization and is required for Mg2+ efflux activity. J Biol Chem 293:19998-20007
Xu, Caishuang; Kozlov, Guennadi; Wong, Kathy et al. (2016) Crystal Structure of the Salmonella Typhimurium Effector GtgE. PLoS One 11:e0166643
Cogliati, Massimo; Zani, Alberto; Rickerts, Volker et al. (2016) Multilocus sequence typing analysis reveals that Cryptococcus neoformans var. neoformans is a recombinant population. Fungal Genet Biol 87:22-9
Oot, Rebecca A; Kane, Patricia M; Berry, Edward A et al. (2016) Crystal structure of yeast V1-ATPase in the autoinhibited state. EMBO J 35:1694-706
Lucido, Michael J; Orlando, Benjamin J; Vecchio, Alex J et al. (2016) Crystal Structure of Aspirin-Acetylated Human Cyclooxygenase-2: Insight into the Formation of Products with Reversed Stereochemistry. Biochemistry 55:1226-38
Bauman, Joseph D; Harrison, Jerry Joe E K; Arnold, Eddy (2016) Rapid experimental SAD phasing and hot-spot identification with halogenated fragments. IUCrJ 3:51-60

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