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Mark                           O'Brian

Mark R. O'Brian PhD

Department of Biochemistry

Professor and Interim Chair

Specialty/Research Focus

Gene Expression; Microbial Pathogenesis; Molecular and Cellular Biology; Regulation of metabolism

 
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Professional Summary:

The adaptive success of bacteria depends, in part, on the ability to sense and respond to their environment. Metals such as iron and manganese are important nutrients that can often be limiting, and therefore cellular metabolism must be modified to either scavenge the nutrients or use alternative processes that do not require the metal.

Bradyrhizobium japonicum belongs to a group of related organisms that form close or intracellular and related bacteria that form an intracellular relationship with eukaryotes in a pathogenic or symbiotic context. This bacterium serves as a model to study related pathogens that are refractive to genetic and biochemical study.

One project involves understanding the mechanisms by which cells maintain iron homeostasis at the level of gene expression. We discovered the global transcriptional regulator Irr that controls iron-dependent processes. Irr is stable only under iron limitation, where it positively and negatively controls target genes. We are interested in understanding the mechanism of this conditional stability, how Irr regulates genes, and the functions of numerous genes under its control.

We initiated a new project to understand the requirement for manganese in cellular processes, how it is acquired from the environment, and how manganese controls gene expression. Also, we identified cross-talk between regulators that control iron and manganese homeostasis and are pursuing this unique mechanism.

Education and Training:
  • Postdoctoral Fellow, Johns Hopkins University (1988)
  • PhD, Biology, Johns Hopkins University (1984)
  • BS, State University of New York at Albany (1980)
Employment:
  • Professor, State University of New York at Buffalo (1999-present)
  • Associate Professor, State University of New York at Buffalo (1994–1999)
  • Assistant Professor, State University of New York at Buffalo (1988–1994)

Research Expertise:
  • Control of metal homeostasis: The adaptive success of bacteria depends, in part, on the ability to sense and respond to their environment. Metals such as iron and manganese are important nutrients that can often be limiting, and therefore cellular metabolism must be modified to either scavenge the nutrients or use alternative processes that do not require the metal. Bradyrhizobium japonicum belongs to a group of related organisms that form close or intracellular and related bacteria that form an intracellular relationship with eukaryotes in a pathogenic or symbiotic context. This bacterium serves as a model to study related pathogens that are refractive to genetic and biochemical study. One project involves understanding the mechanisms by which cells maintain iron homeostasis at the level of gene expression. We discovered the global transcriptional regulator Irr that controls iron-dependent processes. Irr is stable only under iron limitation, where it positively and negatively controls target genes. We are interested in understanding the mechanism of this conditional stability, how Irr regulates genes, and the functions of numerous genes under its control. We initiated a new project to understand the requirement for manganese in cellular processes, how it is acquired from the environment, and how manganese controls gene expression. Also, we identified cross-talk between regulators that control iron and manganese homeostasis and are pursuing this unique mechanism.
Grants and Sponsored Research:
  • April 2012–March 2016
    Regulation of bacterial manganese metabolism
    National Institutes of Health
    Role: Principal Investigator
    $1,139,888
  • December 2008–November 2013
    Regulation of bacterial heme metabolism
    NIH
    Role: Principal Investigator
    $1,256,600

Journal Articles:
See All (64 Total) >
Books and Book Chapters:
  • O‘Brian, M.R. Fabiano, E.. Mechanisms and regulation of iron homeostasis in the Rhizobia. 2010.
  • O‘Brian MR. Heme Biosynthesis. 2009; 5.
  • Finan, T.M. O‘Brian, M.R. Layzell, D.B. Vessey, J.K. Newton, W.. Nitrogen Fixation: Global Perspectives. 2002.
  • O'Brian, M.R. Thoeny-Meyer, L.. Biochemistry, regulation and genomics of heme biosynthesis in prokaryotes. Advances in Microbial Physiology. 2002; 46.
  • O'Brian, M.R.. Heme biosynthesis and function in he Rhizobium-legume symbiosis. Prokaryotic Nitrogen Fixation: A Model System for the Analysis of a Biological Process. 2000.
  • O'Brian, M.R.. Regulation of bacterial heme biosynthesis by iron. Iron Metabolism: Inorganic Biochemistry and Regulatory Mechanisms. 1999.
  • Chauhan, S. O'Brian, M.R.. Regulation of Bradyrhizobium japonicum hemB, a heme biosynthesis gene.. Biological Fixation of Nitrogen for Ecology and Sustainable Agriculture. 1997.

Professional Memberships:
  • American Association for the Advancement of Science (1984)
  • American Society for Biochemistry and Microbiology (1984)
  • American Society for Microbiology (1981)
Service Activities:
  • Interim Chair, Department of Biochemistry (2013)
  • Member, Biochemistry Chair Search Committee (2013)
  • Director of Graduate Studies, Dept. of Biochemistry (2011)
  • Instructor, Short course in microbiology, Montevideo, Uruguay (2009)
  • Editor, Focus issue on legume biology (2009)
  • Monitoring Editor, Plant Physiology (2005–2010)
  • Chair, Gordon Research Conference, Biology and Chemistry of Tetrapyrroles (2004)
  • Editorial Board, Applied and Environmental Microbiology (2001–2009)

Clinical Specialties:
Clinical Offices:
Insurance Accepted:

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Contact Information

Department of Biochemistry
140 Farber Hall
State University of New York at Buffalo
Buffalo, NY 14214
Phone: (716) 829-3200
Email: mrobrian@buffalo.edu


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