Peggy Cotter | Professor and AAM Fellow, University of North Carolina

peggy-cotter-180x180Peggy Cotter earned a B.A. with majors in Microbiology and Psychobiology and a Ph.D. in Microbiology and Molecular Genetics from UCLA. 

She was a post-doctoral fellow with Jeff F. Miller in Microbiology and Immunology in the UCLA School of Medicine before establishing her own laboratory at the University of California, Santa Barbara in 2001. Dr. Cotter moved to the University of North Carolina – Chapel Hill in July 2009 where she is currently a Professor of Microbiology and Immunology in the School of Medicine. She has been an Editor for Molecular Microbiology since 2006, will chair the NIH PCMB study section beginning July 1, 2017, and has held several leadership positions within the American Society for Microbiology (ASM).

She was elected as a fellow of the American Academy of Microbiology in 2012. She is currently the President-elect of the ASM and will serve as President beginning July 1, 2017.

Are Contact-Dependent Inhibition (CDI) System-encoding genes Facultative, Multicolored Greenbeards?

Contact-dependent growth inhibition (CDI) systems were discovered based on the observation that Escherichia coli producing the CdiA/CdiB two-partner secretion pathway proteins could inhibit the growth of non-CdiA/CdiB-producing E. coli upon cell-cell contact. Subsequent analyses showed that the C-termini of the large CdiA proteins (called the CdiA-CT) contain the toxic activity and that a small immunity protein (CdiI) protects against auto-inhibition. We now know that CDI systems are widespread among Gram-negative proteobacteria, that the CdiA-CT and CdiI polypeptides are highly variable, and that CdiI proteins protect in an allele-specific manner. Using Burkholderia thailandensis as a model, we found that in addition to mediating interbacterial competition, CDI systems can induce changes in gene expression between sibling bacteria that result in cooperative behaviors such as biofilm formation. Hence, CDI system proteins mediate competition between ‘non-self’ neighbors and cooperation between ‘self’ neighbors. More recently, we discovered evidence that CDI system-encoding genes are on mobile genomic islands. Our data support a model in which CDI system-encoding genes mediate self-transfer into non-self neighbors, either converting those neighbors to cooperating ‘self’ bacteria or ensuring propagation of the CDI system-encoding genes to descendants if the non-self neighbors are capable of out-competing the resident population.