Andrew B. Buermeyer

Requirement for PCNA in DNA Mismatch Repair at a Step Preceding DNA Resynthesis

A two-hybrid system was used to screen yeast and human expression libraries for proteins that interact with mismatch repair proteins. PCNA was recovered from both libraries and shown in the case of yeast to interact with both MLH1 and MSH2. A yeast strain containing a mutation in the PCNA gene had a strongly elevated mutation rate in a dinucleotide repeat, and the rate was not further elevated in a strain also containing a mutation in MLH1. Mismatch repair activity was examined in human cell extracts using an assay that does not require DNA repair synthesis. Activity was inhibited by p21WAF1 or a p21 peptide, both of which bind to PCNA, and activity was restored to inhibited reactions by addition of PCNA. The data suggest a PCNA requirement in mismatch repair at a step preceding DNA resynthesis. The ability of PCNA to bind to MLH1 and MSH2 may reflect linkage between mismatch repair and replication and may be relevant to the roles of mismatch repair proteins in other DNA transactions.

In memory of John Bruce Hays (1937-2014).

[ sites stimulates genetic recombination of bacteriophage lambda, Cell 28 (1982) Our dear friend and colleague, John Hays, passed away January rd in Corvallis, Oregon. John was a lifelong non-smoker and avid portsman, but in a cynical twist of fate, he learned only a year ago hat he was afflicted with stage 4 adenocarcinoma of the lung. John was born June 21, 1937 in Springfield, Illinois and gradated from Monrovia High School, California, in 1954. He turned own a scholarship to Stanford University to spend two years in he work/study curriculum at Deep Springs, a unique small college n a ranch near Bishop, California, where he was trained in rhetoric, omposition and the liberal arts; while milking cows, learning to ide horses, rounding up cattle and participating in student governent. John then completed an undergraduate major in Chemistry nd Mathematics at the University of New Mexico, Albuquerque, efore serving three years in the U.S. Navy. He continued in the aval Reserve while carrying out graduate studies at the University f California, San Diego, to receive a doctorate in Physical Chemistry n 1967. Following postdoctoral study at Johns Hopkins University, ohn joined the faculty at the University of Maryland, rising through he academic ranks from Assistant Professor to Professor of Chemstry in 1982. He fulfilled his long-term desire to return to the West n 1987, to assume Chairmanship of the Department of Agriculural Chemistry (Now, Environmental and Molecular Toxicology) t Oregon State University, Corvallis. He was a Professor in that epartment from 1998 until his death. Following his retirement n 2010 John continued his research as an emeritus. His daugher, Laura, writes: “As the ever-dedicated scientist, he was reading apers and working on manuscripts almost until the end.” John’s research career began in the field of lactose metabolism n gram-positive bacteria, [1]; his interest then shifted abruptly to ecombination in phage lambda, specifically on the role of DNA esions in the induction of recombination [2]. The move to Corallis also engendered a shift toward research on DNA repair and utagenesis in a variety of eukaryotic models including Xenopus aevis and other, less mundane, amphibians [3], and then Arabidopis thaliana [4]. John is particularly well known for his elegant series f studies on the coupling between recognition of base mispairing nd excision in the DNA mismatch repair pathway in mammalian ells [5]. John Hays was an invited speaker and session chair for many cientific conferences, particularly Gordon Conferences, where he as appreciated as one of the most avid and articulate discussants. [