Mark R. O‘Brian PhD

Mark O‘Brian

Mark R. O‘Brian
PhD

Professor and Chair

Department of Biochemistry

Jacobs School of Medicine & Biomedical Sciences


Specialty/Research Focus

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

Contact Information
Department of Biochemistry
University at Buffalo
955 Main Street, Room 4102
Buffalo, NY 14203
Phone: (716) 829-3200
mrobrian@buffalo.edu



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 a close or 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.

Our lab seeks to understand 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. Moreover, Irr integrates iron homeostasis with manganese metabolism, providing a link between the two nutrients.

Identifying the Irr regulon and iron stimulon has given us important clues into how bacteria traffic iron into and out of the cell. Recent work suggests that B. japonicum not only adapts at the level of gene expression, but can mutate rapidly to accommodate new nutritional sources in the environment.

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 nutritional 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:

  • May 2017–March 2021
    Bacterial adaptation to iron stress
    National Institutes of Health
    Role: Principal Investigator
    $1,271,904

Journal Articles:

See all (65 more)

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.
  • O'Brian, M.R. Thoeny-Meyer, L.. Biochemistry, regulation and genomics of heme biosynthesis in prokaryotes. Advances in Microbial Physiology. 2002; 46.
  • Finan, T.M. O‘Brian, M.R. Layzell, D.B. Vessey, J.K. Newton, W.. Nitrogen Fixation: Global Perspectives. 2002.
  • 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–present)
  • American Society for Biochemistry and Microbiology (1984–present)
  • American Society for Microbiology (1981–present)

Service Activities:

  • Chair, Department of Biochemistry; Chair (2015–present)
  • Interim Chair, Department of Biochemistry (2013–2015)
  • Member, Biochemistry Chair Search Committee (2013)
  • Director of Graduate Studies, Dept. of Biochemistry (2011–2013)
  • Instructor, Short course in microbiology, Montevideo, Uruguay (2009–present)
  • Editor, Focus issue on legume biology (2009–present)
  • Monitoring Editor, Plant Physiology (2005–2010)
  • Chair, Gordon Research Conference, Biology and Chemistry of Tetrapyrroles (2004–present)
  • Editorial Board, Applied and Environmental Microbiology (2001–2009)

School News:

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Clinical Specialties:

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Contact Information

Department of Biochemistry
University at Buffalo
955 Main Street, Room 4102
Buffalo, NY 14203
Phone: (716) 829-3200
mrobrian@buffalo.edu