Gabriele Nordsiek | PubMed Health

PubMed2006

A human-horse comparative map based on equine BAC end sequences.

In an effort to increase the density of sequence-based markers for the horse genome we generated 9473 BAC end sequences (BESs) from the CHORI-241 BAC library with an average read length of 677 bp. BLASTN searches with the BESs revealed 4036 meaningful hits (E <or= 10(-5)) in the human genome that provide useful markers for the human-horse comparative map. The 4036 BLASTN hits allowed the anchoring of 3079 BAC clones to the human genome, on average one corresponding equine BAC clone per megabase of human DNA. We used the BLASTN anchored BESs for an in silico prediction of the gene content and chromosome assignment of comparatively mapped equine BAC clones. As a first verification of our in silico mapping strategy we placed 19 equine BESs with matches to HSA6 onto the RH map. All markers were assigned to the predicted localizations on ECA10, ECA20, and ECA31, respectively.

Animals↗

PubMed2002

The biosynthesis of the aromatic myxobacterial electron transport inhibitor stigmatellin is directed by a novel type of modular polyketide synthase.

Deductions from the molecular analysis of the 65,000-bp stigmatellin biosynthetic gene cluster are reported. The biosynthetic genes (stiA-J) encode an unusual bacterial modular type I polyketide synthase (PKS) responsible for the formation of this aromatic electron transport inhibitor produced by the myxobacterium Stigmatella aurantiaca. Involvement of the PKS gene cluster in stigmatellin biosynthesis is shown using site-directed mutagenesis. One module of the PKS is assumed to be used iteratively during the biosynthetic process, which seems to involve an unusual transacylation of the biosynthetic intermediate from an acyl carrier protein domain back to the preceding ketosynthase domain. Finally, the polyketide chain which is presumably catalyzed by a novel C-terminal domain in StiJ that does not resemble thioesterases, is cyclized and aromatized. The presented results of feeding experiments are in good agreement with the proposed biosynthetic scheme. In contrast to all other PKS type I systems reported to date, each module of StiA-J is encoded on a separate gene. The gene cluster contains a "stand alone" O-methyltransferase and two unusual O-methyltransferase domains embedded in the PKS. In addition, inactivation of a cytochrome P450 monooxygenase-encoding gene involved in post-PKS hydroxylation of the aromatic ring leads to the formation of two novel stigmatellin derivatives.

Base Sequence↗