Life Sciences Commons^™

Pot1 Proteins In Green Algae And Land Plants: Dna-Binding Properties And Evidence Of Co-Evolution With Telomeric Dna, Eugene V. Shakirov, Xiangyu Song, Jessica A. Joseph, Dorothy E. Shippen

Biological Sciences Faculty Research

Telomeric DNA terminates with a single-stranded 3′ G-overhang that in vertebrates and fission yeast is bound by POT1 (Protection Of Telomeres). However, no in vitro telomeric DNA binding is associated with Arabidopsis POT1 paralogs. To further investigate POT1–DNA interaction in plants, we cloned POT1 genes from 11 plant species representing major branches of plant kingdom. Telomeric DNA binding was associated with POT1 proteins from the green alga Ostreococcus lucimarinus and two flowering plants, maize and Asparagus. Site-directed mutagenesis revealed that several residues critical for telomeric DNA recognition in vertebrates are functionally conserved in plant POT1 proteins. However, the plant proteins …

Expression And Function Of Hypoxia Inducible Factor-1 Alpha In Human Melanoma Under Non-Hypoxic Conditions, Caroline N. Mills, Sandeep S. Joshi, Richard M. Niles

Biochemistry and Microbiology

Background

Hypoxia inducible factor-1 alpha (HIF-1α) protein is rapidly degraded under normoxic conditions. When oxygen tensions fall HIF-1α protein stabilizes and transactivates genes involved in adaptation to hypoxic conditions. We have examined the normoxic expression of HIF-1α RNA and protein in normal human melanocytes and a series of human melanoma cell lines isolated from radial growth phase (RGP), vertical growth phase (VGP) and metastatic (MET) melanomas.

Results

HIF-1α mRNA and protein was increased in RGP vs melanocytes, VGP vs RGP and MET vs VGP melanoma cell lines. We also detected expression of a HIF-1α mRNA splice variant that lacks part …

Pot1‐Independent Single‐Strand Telomeric Dna Binding Activities In Brassicaceae, Eugene V. Shakirov, Thomas D. Mcknight, Dorothy E. Shippen

Biological Sciences Faculty Research

Telomeres define the ends of linear eukaryotic chromosomes and are required for genome maintenance and continued cell proliferation. The extreme ends of telomeres terminate in a single‐strand protrusion, termed the G‐overhang, which, in vertebrates and fission yeast, is bound by evolutionarily conserved members of the POT1 (protection of telomeres) protein family. Unlike most other model organisms, the flowering plant Arabidopsis thaliana encodes two divergent POT1‐like proteins. Here we show that the single‐strand telomeric DNA binding activity present in A. thaliana nuclear extracts is not dependent on POT1a or POT1b proteins. Furthermore, in contrast to POT1 proteins from yeast and vertebrates, …