Makkuni Jayaram

Jayaram, Makkuni
Professor in Molecular Genetics & Microbiology

E-mail: jayaram@icmb.utexas.edu

Website: http://www.sbs.utexas.edu/jayaram/jayaramlab.htm

Main Office: NMS 2.116
Phone: 471-0966

Alternate Office: NMS 2.210
Phone: 471-5537

Mailing Address:
The University of Texas at Austin - ICMB
1 University Station A5000
100 E. 24th St.
Austin, TX 78712-1095

Graduate Students:

  • Cui, Hong
  • Huang, Chu-Chun
  • Liu , Yen-Ting

    • Post Doc Students:

  • Ghosh, Santanu
  • Hajra, Sujata

    • Research Summary:
       

    We study the molecular mechanisms by which extrachromosomal DNA elements maintain themselves stably and at relatively high copy numbers without endangering their host organisms. The model system we employ is the 2 micron plasmid of Saccharomyces cerevisiae. The plasmid has a copy number of approximately 60 per cell, and is rarely lost during cell division. The high plasmid stability is ensured by a partitioning system that includes two plasmid proteins and a cis-acting DNA locus. The plasmid also utilizes an amplification mechanism to compensate for rare stochastic downward fluctuations in copy number. A site-specific DNA recombination system encoded by the plasmid is responsible for this copy number control.

    The research projects in the laboratory explore recombination mechanisms, test models for recombination mediated DNA amplification and examine plasmid segregation using tools of molecular genetics and cell biology.


     
    Research Images:

    Sister-to-sister segregation of the yeast plasmid - The yeast plasmid is a multicopy benign parasite DNA element that exploits the chromosome segregation machinery for its stable persistence. Tagging reporter plasmids with two colors, red and green, reveals a ssiter-to-sister segregation mechanism: red from red and green from green.

     
    Publications:
    Split target specificity of ResT: a design for protein delivery, site selectivity and regulation of enzyme activity (2007) Mol. Microbiol. 64, 574-579.
    Protein induced local DNA bends regulate global topology of recombination products (2007) J. Mol. Biol. 368, 170-182.
    Unveiling hidden catalytic activities of the conserved His-trp-III in tyrosine recombinases (2007) J. Mol. Biol. 368, 183-196.
    The centromere-specific histone variant Cse4p (CENP-A) is essential for chromatin architecture at the yeast 2 micron circle partitioning locus. (2006) J. Cell Biol. 174, 779-790.
    Evolution of a site-specific variant that utilizes native genomic sequences as recombination target sites. (2006) Nucleic Acids Res. i34, 5259-5269.
    The Mu transposase wraps distant DNA sites within a functional transpososome in the absence of DNA supercoiling (2005) J. Biol. Chem. 280, 6149-6156.
    The 2 micron plasmid causes cell death in Saccharomyces with a mutation in Ulp1 protease (2005) Mol. Cell. Biol. 25, 4299-4310.
    A novel role for the mitotic spindle in promoting DNA segregation in yeast: promoting 2 micron plasmid-cohesin association (2005) Mol. Cell. Biol. 25, 4283-4298.
    Site-specific recombination and partitioning systems in the stable high-copy propagation of the 2 micron yeast plasmid (2004) Prog. Nucleic Acids Res Mol. Biol. 77, 127-172.
    Mutations in a partitioning protein and altered chromatin structure at the partitioning locus prevent cohesin recruitment by the Saccharomyces cerevisiae plasmid and cause plasmid missegregation (2004) Mol. Cell. Biol. 24, 5290-5303.
    Recombination of hybrid target sites by binary combinations of Flp variants: Mutations that foster interprotomer collaboration and enlarge substrate tolerance (2004) J. Mol. Biol. 339, 365-378.

     
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