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BIOGRAPHY:
Dr. Jerzmanowski is Professor, Group Leader, and Head of the
Laboratory of Plant Molecular Biology at the Institute of Experimental
Plant Biology, Faculty of Biology, University of Warsaw, Poland. He
received his Ph.D. in biochemistry, and his D.Habil. from the
University of Warsaw. He became a Junior Research Associate in the
Department of Biochemistry at the University of Warsaw and did
postdoctoral training in the Biophysics Laboratory of Portsmouth
Polytechnic in the United Kingdom. He also conducted research in the
Department of Biochemistry in the Institute of Forest Botany at the
University of Göttingen, Germany, and at the Department of
Molecular and Cell Biology at the University of California Berkeley. He
was a Visiting Scientist at the Institut de Biologie Moléculaire
et Cellulaire du Centre Conseil National de Recherche Scientifique in
Strasbourg, France. He also has served as a Fellow of the Alexander von
Humboldt Foundation of the Federal Republic of Germany. He is a member
of, and was awarded the 2003 L. Marchlewski Medal by, the Polish
Academy of Sciences. This is his second HHMI International Research
Scholar award. His current research focuses on chromatin remodeling in
the model plant Arabidopsis thaliana.
RESEARCH ABSTRACT SUMMARY:
Role of Chromatin Proteins in Maintaining the Specific Patterns of DNA Methylation in Arabidopsis thaliana
In mammals and flowering plants, DNA methylation is a key molecular
signal used to distinguish between active and inactive genes. Deficient
in DNA methylation 1 (DDM1) protein is required to maintain DNA
methylation status in Arabidopsis thaliana. We used a
purified recombinant DDM1 protein to investigate whether it can remodel
chromatin in vitro. We show that DDM1 is an ATPase stimulated by both
naked and nucleosomal DNA. It binds to chromatin and induces nucleosome
repositioning and disruption of histone DNA contacts. The enzymatic
activities of DDM1 are not affected by DNA methylation. To investigate
the involvement of chromatin structural proteins in DNA methylation, we
used double-stranded RNA (dsRNA) silencing to suppress all the
H1 genes of A. thaliana. Plants with a greater than 90
percent reduction in H1 expression exhibited a spectrum of
phenotypic defects resembling those observed in DNA hypomethylation
mutants. We are analyzing the molecular background of these phenotypes.
Photo: Kent Kallberg, Kallberg Studios
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