Biomedical subjects

Stefanie Hartmann

Publications and source records attributed to Stefanie Hartmann.

3 recordsLinked to original sources

PubMed2006

Phytome: a platform for plant comparative genomics.

Phytome is an online comparative genomics resource that can be applied to functional plant genomics, molecular breeding and evolutionary studies. It contains predicted protein sequences, protein family assignments, multiple sequence alignments, phylogenies and functional annotations for proteins from a large, phylogenetically diverse set of plant taxa. Phytome serves as a glue between disparate plant gene databases both by identifying the evolutionary relationships among orthologous and paralogous protein sequences from different species and by enabling cross-references between different versions of the same gene curated independently by different database groups. The web interface enables sophisticated queries on lineage-specific patterns of gene/protein family proliferation and loss. This rich dataset is serving as a platform for the unification of sequence-anchored comparative maps across taxonomic families of plants. The Phytome web interface can be accessed at the following URL: http://www.phytome.org. Batch homology searches and bulk downloads are available upon free registration.

Databases, Genetic↗

PubMed2003

High-frequency gene transfer from the chloroplast genome to the nucleus.

Eukaryotic cells arose through endosymbiotic uptake of free-living bacteria followed by massive gene transfer from the genome of the endosymbiont to the host nuclear genome. Because this gene transfer took place over a time scale of hundreds of millions of years, direct observation and analysis of primary transfer events has remained difficult. Hence, very little is known about the evolutionary frequency of gene transfer events, the size of transferred genome fragments, the molecular mechanisms of the transfer process, or the environmental conditions favoring its occurrence. We describe here a genetic system based on transgenic chloroplasts carrying a nuclear selectable marker gene that allows the efficient selection of plants with a nuclear genome that carries pieces transferred from the chloroplast genome. We can select such gene transfer events from a surprisingly small population of plant cells, indicating that the escape of genetic material from the chloroplast to the nuclear genome occurs much more frequently than generally believed and thus may contribute significantly to intraspecific and intraorganismic genetic variation.

Base Sequence↗

PubMed2002

Investigation of the microheterogeneity and aglycone specificity-conferring residues of black cherry prunasin hydrolases.

In black cherry (Prunus serotina Ehrh.) seed homogenates, (R)-amygdalin is degraded to HCN, benzaldehyde, and glucose by the sequential action of amygdalin hydrolase (AH), prunasin hydrolase (PH), and mandelonitrile lyase. Leaves are also highly cyanogenic because they possess (R)-prunasin, PH, and mandelonitrile lyase. Taking both enzymological and molecular approaches, we demonstrate here that black cherry PH is encoded by a putative multigene family of at least five members. Their respective cDNAs (designated Ph1, Ph2, Ph3, Ph4, and Ph5) predict isoforms that share 49% to 92% amino acid identity with members of glycoside hydrolase family 1, including their catalytic asparagine-glutamate-proline and isoleucine-threonine-glutamate-asparagine-glycine motifs. Furthermore, consistent with the vacuolar/protein body location and glycoprotein character of these hydrolases, their open reading frames predict N-terminal signal sequences and multiple potential N-glycosylation sites. Genomic sequences corresponding to the open reading frames of these PHs and of the previously isolated AH1 isoform are interrupted at identical positions by 12 introns. Earlier studies established that native AH and PH display strict specificities toward their respective glucosidic substrates. Such behavior was also shown by recombinant AH1, PH2, and PH4 proteins after expression in Pichia pastoris. Three amino acid moieties that may play a role in conferring such aglycone specificities were predicted by structural modeling and comparative sequence analysis and tested by introducing single and multiple mutations into isoform AH1 by site-directed mutagenesis. The double mutant AH ID (Y200I and G394D) hydrolyzed prunasin at approximately 150% of the rate of amygdalin hydrolysis, whereas the other mutations failed to engender PH activity.

Aldehyde-Lyases↗