|
|
|
|
|
|
Fibronectin Binding to the Salmonella enterica Serotype Typhimurium ShdA Autotransporter Protein Is Inhibited by a Monoclonal Antibody Recognizing the A3 Repeat. Robert A. Kingsley, 2004.ShdA is a large outer membrane protein of the autotransporter family whose passenger domain binds the extracellular matrix proteins fibronectin and collagen I, possibly by mimicking the host ligand heparin . The ShdA passenger domain consists of  1,500
amino acid residues that can be divided into two regions based
on features of the primary amino acid sequence: an N-terminal
nonrepeat region followed by a repeat region composed of two types of
imperfect direct amino acid repeats, called type A and type B . The
repeat region bound bovine fibronectin with an affinity similar to
that for the complete ShdA passenger domain, while the nonrepeat
region exhibited comparatively low fibronectin-binding activity . A
number of fusion proteins containing truncated fragments of the
repeat region did not bind bovine fibronectin . However, binding of
the passenger domain to fibronectin was inhibited in the presence of
immune serum raised to one truncated fragment of the repeat region
that contained repeats A2, B8, A3, and B9 . Furthermore, a monoclonal
antibody that specifically recognized an epitope in a recombinant
protein containing the A3 repeat inhibited binding of ShdA to
fibronectin .
Genomic Diversity of Erwinia carotovora subsp . carotovora and Its Correlation with Virulence. Mee-Ngan Yap, 2004.We used genetic and biochemical methods to examine the genomic diversity of the enterobacterial plant pathogen Erwinia carotovora subsp . carotovora . The results obtained with each method showed that E . carotovora subsp . carotovora strains isolated from one ecological niche, potato plants, are surprisingly diverse compared to related pathogens . A comparison of 23 partial mdh sequences revealed a maximum pairwise difference of 10.49% and an average pairwise difference of 2.13%, values which are much greater than the maximum variation (1.81%) and average variation (0.75%) previously reported for Escherichia coli. Pulsed-field gel electrophoresis analysis of I-CeuI-digested genomic DNA revealed seven rrn operons in all E . carotovora subsp . carotovora strains examined except strain WPP17, which had only six copies . We identified 26 I-CeuI restriction fragment length polymorphism patterns and observed significant polymorphism in fragment sizes ranging from 100 to 450 kb for all strains . We detected large plasmids in two strains, including the model strain E . carotovora subsp . carotovora 71 . The two least virulent strains had an unusual chromosomal structure, suggesting that a particular pulsotype is correlated with virulence . To compare chromosomal organization of multiple enterobacterial genomes, several genes were mapped onto I-CeuI fragments . We identified portions of the genome that appear to be conserved across enterobacteria and portions that have undergone genome rearrangements . We found that the least virulent strain, WPP17, failed to oxidize cellobiose and was missing several hrp and hrc genes . The unexpected variability among isolates obtained from clonal hosts in one region and in one season suggests that factors other than the host plant, potato, drive the evolution of this common environmental bacterium and key plant pathogen . Interaction of the Initiator Protein of an IncB Plasmid with Its Origin of DNA Replication. T. Betteridge, 2003.The replication initiator protein RepA of the IncB plasmid pMU720 was purified and used in DNase I protection assays in vitro . RepA protected a 68-bp region of the origin of replication of pMU720 . This region, which lies immediately downstream of the DnaA box, contains four copies of the sequence motif 5'AANCNGCAA3' . Mutational analyses identified this sequence as the binding site specifically recognized by RepA (the RepA box) . Binding of RepA to the RepA boxes was ordered and sequential, with the box closest to the DnaA binding site (box 1) occupied first and the most distant boxes (boxes 3 and 4) occupied last . However, only boxes 1, 2, and 4 were essential for origin activity, with box 3 playing a lesser role . Changing the spacing between box 1 and the other three boxes affected binding of RepA in vitro and origin activity in vivo, indicating that the RepA molecules bound to oriB interact with one another .
|
© 2005
Transgalactic Ltd (manufacturer of Bioscreen C software) |
Privacy Statement | P.O. Box
1393, 00101 Helsinki, Finland,
Last modified: May 25, 2005
| ||||||
