The long-term goal of this research is to gain an integrated view of how S. meliloti establishes the chronic intracellular infection that underlies its symbiosis and to use these findings to gain insights into the molecular strategies used by certain chronic intracellular mammalian pathogens. The proposal includes experiments analyzing a gene (YbeY/Smc01113), originally discovered because of its importance for symbiosis, that is present in every bacterium and encodes a previously undiscovered RNase whose function is required for the maturation of all three ribosomal rRNAs - 16S, 23S, and 5S. The human homolog of YbeY, C21ORF57, encoded in the Down Syndrome Critical Region of chromosome 21, is also an RNase that is critically required for mitochondrial function in human cells. We will to continue to investigate the physiological roles of YbeY, including characterizing its relationship to other RNases and investigating its interaction with certain ribosome maturation factors. A high-throughput screen has been validated and will be used to screen for small molecule YbeY inhibitors that could serve as lead compounds for the development of a new antibiotic. We will continue to characterize the biochemical properties of YbeY, its interactions with partner proteins, and determine the structure of YbeY in a complex with an RNA substrate. We will continue to use cell lines and transgenic mice to investigate the roles of the human YbeY homolog C21ORF57 and a possible connection to Down syndrome. We will continue our efforts to determine the role of bacterial cell cycle control in bacteroid differentiation of S. meliloti during symbiosis, including analyzing the importance of proteolytic control of the key cell cycle regulator CtrA. We will continue to investigate other functions important for S. meliloti symbiosis and their possible roles in Brucella pathogenesis, including determining whether certain genes essential for S. meliloti symbiosis are also necessary for Brucella pathogenesis and analyzing the importance of small RNA regulation in S. meliloti symbiosis. There is a critical need for new antibiotics since only three new classes of antibiotics have been discovered since 1962 and the emergence of antibiotic-resistant and """"""""superbugs"""""""" threatens our ability to treat infectious diseases. A drug that inhibits YbeY could be a new class of broad-spectrum antibiotic. If C21ORF57 proves to contribute to the pathology of trisomy 21, an inhibitor of C21ORF57 could be the first drug to treat Down syndrome. Work on S. meliloti symbiosis is helping to identify Brucella genes necessary for pathogenesis that could be new drug targets. This is important because Brucella infections are difficult to treat and Brucella is regarded as a bioterrorism threat. Brucella mutants whose virulence is appropriately attenuated could be vaccine candidates as there is currently no vaccine against Brucella. The project has offered novel insights into the biosynthesis of B12, a critically important vitamin for human health, and will continue to explore its role in biology. Finally, our work on the S. meliloti-Medicago symbiosis serves as a model for many symbioses found in Nature.

Public Health Relevance

A drug that inhibits YbeY could be a new class of broad-spectrum antibiotic and, if C21ORF57 proves to contribute to the pathology of trisomy 21, an inhibitor of C21ORF57 could be the first drug to treat Down syndrome. Work on S. meliloti symbiosis is helping to identify Brucella genes necessary for pathogenesis that could be new drug targets. The project has offered novel insights into the biosynthesis of B12, a critically important vitamin for human health, and will continue to explore the role of vitamin B12 in biology.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
2R01GM031030-29
Application #
7991548
Study Section
Prokaryotic Cell and Molecular Biology Study Section (PCMB)
Program Officer
Singh, Shiva P
Project Start
1982-07-01
Project End
2014-07-31
Budget Start
2010-09-27
Budget End
2011-07-31
Support Year
29
Fiscal Year
2010
Total Cost
$442,468
Indirect Cost
Name
Massachusetts Institute of Technology
Department
Biology
Type
Schools of Arts and Sciences
DUNS #
001425594
City
Cambridge
State
MA
Country
United States
Zip Code
02139
Ghosal, Anubrata; Babu, Vignesh M P; Walker, Graham C (2018) Elevated Levels of Era GTPase Improve Growth, 16S rRNA Processing, and 70S Ribosome Assembly of Escherichia coli Lacking Highly Conserved Multifunctional YbeY Endoribonuclease. J Bacteriol 200:
Budnick, James A; Sheehan, Lauren M; Colquhoun, Jennifer M et al. (2018) Endoribonuclease YbeY Is Linked to Proper Cellular Morphology and Virulence in Brucella abortus. J Bacteriol 200:
Arnold, Markus F F; Shabab, Mohammed; Penterman, Jon et al. (2017) Genome-Wide Sensitivity Analysis of the Microsymbiont Sinorhizobium meliloti to Symbiotically Important, Defensin-Like Host Peptides. MBio 8:
Ghosal, Anubrata; Köhrer, Caroline; Babu, Vignesh M P et al. (2017) C21orf57 is a human homologue of bacterial YbeY proteins. Biochem Biophys Res Commun 484:612-617
Shabab, Mohammed; Arnold, Markus F F; Penterman, Jon et al. (2016) Disulfide cross-linking influences symbiotic activities of nodule peptide NCR247. Proc Natl Acad Sci U S A 113:10157-62
Vercruysse, Maarten; Köhrer, Caroline; Shen, Yang et al. (2016) Identification of YbeY-Protein Interactions Involved in 16S rRNA Maturation and Stress Regulation in Escherichia coli. MBio 7:
Pini, Francesco; De Nisco, Nicole J; Ferri, Lorenzo et al. (2015) Cell Cycle Control by the Master Regulator CtrA in Sinorhizobium meliloti. PLoS Genet 11:e1005232
Price, Paul A; Tanner, Houston R; Dillon, Brett A et al. (2015) Rhizobial peptidase HrrP cleaves host-encoded signaling peptides and mediates symbiotic compatibility. Proc Natl Acad Sci U S A 112:15244-9
De Nisco, Nicole J; Abo, Ryan P; Wu, C Max et al. (2014) Global analysis of cell cycle gene expression of the legume symbiont Sinorhizobium meliloti. Proc Natl Acad Sci U S A 111:3217-24
Penterman, Jon; Abo, Ryan P; De Nisco, Nicole J et al. (2014) Host plant peptides elicit a transcriptional response to control the Sinorhizobium meliloti cell cycle during symbiosis. Proc Natl Acad Sci U S A 111:3561-6

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