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Biomedical subjects

Peter Sommer

Publications and source records attributed to Peter Sommer.

4 recordsLinked to original sources
PubMed2004

The effect of decreasing oxygen feed rates on growth and metabolism of Torulaspora delbrueckii.

The effect of decreasing oxygen feed rates on the growth and metabolism of Torulaspora delbrueckii and Saccharomyces cerevisiae in chemostat cultures was investigated. The biosynthetic oxygen requirement, i.e. the minimum specific oxygen consumption rate required for steady-state growth at a dilution rate of 0.10 h(-1), of T. delbrueckii was quantified to be less than 0.1 mmol O(2) g(-1) h(-1). Under strict anaerobiosis, washout of T. delbrueckii occurred, whereas for S. cerevisiae it did not. Under oxygen-limited conditions, the increase in fermentative ability of T. delbrueckii with diminishing oxygen supply was less pronounced than that of S. cerevisiae. These results indicate that T. delbrueckii was more disturbed in its energy balance than S. cerevisiae under strict anaerobiosis, and they may explain why T. delbrueckii exhibits poorer growth than S. cerevisiae under this condition.

Anaerobiosis↗
PubMed2004

APOBEC3G is a single-stranded DNA cytidine deaminase and functions independently of HIV reverse transcriptase.

In the absence of the viral vif gene, human immunodeficiency virus (HIV) may be restricted by the APOBEC3G gene on chromosome 22. The role of the HIV Vif protein is to exclude host cell APOBEC3G from the budding virion. As APOBEC3G shows sequence homology to cytidine deaminases, it is presumed that in the absence of Vif, cytidine residues in the cDNA are deaminated yielding uracil. It is not known if additional proteins mediate APOBEC3G function or if deamination occurs in concert with reverse transcription. This report describes an in vitro assay showing that Baculovirus derived APOBEC3G alone extensively deaminates cDNA independently of reverse transcriptase. It reproduces the dinucleotide context typical of G --> A hypermutants derived from a Delta(vif) virus. By using an RNaseH- form of reverse transcriptase, it was shown that the cDNA has to be free of its RNA template to allow deamination. APOBEC3G deamination of dC or dCTP was not detected. In short, APOBEC3G is a single-stranded DNA cytidine deaminase capable of restricting retroviral replication.

APOBEC-3G Deaminase↗
PubMed2003

Death and the retrovirus.

A flurry of new papers has shown that HIV reverse transcription is vulnerable to G-->A hypermutation. Apparently, cytidine bases in nascent DNA synthesis are lethally edited by the host cell molecule apolipoprotein B editing complex protein (APOBEC) 3G. This death mechanism is circumvented by the HIV viral infectivity factor protein, which prevents APOBEC3G from entering the virion.

APOBEC-3G Deaminase↗