Authors: M Elazar D Halfon I Pechatnikov Y Nitzan
Publish Date: 2007/01/05
Volume: 54, Issue: 2, Pages: 155-161
Abstract
A major Erwinia amylovora outermembrane protein OmpEA and the gene encoding for this protein ompEA were isolated and characterized The native OmpEA protein forms a trimeric structure of approximately 114 kDa This protein demonstrated high resistance to detergents such as SDS and octylglucopyranoside but disaggregated to monomers with a molecular weight MW of approximately 39 kDa after heating at 95°C for 10 minutes in sample buffer The poreforming ability of the oligomeric OmpEA was determined by the liposome swelling assay demonstrating that the oligomeric protein formed nonspecific channels with an exclusion limit of approximately 660 Da On dissociation the monomers did not exhibit poreforming ability The ompEA gene was cloned and sequenced GenBank Accession No DQ184680 Sequence analysis revealed an open reading frame of 1152 bases The deduced aminoacid sequence had 383 amino acids The mature protein consisted of 362 amino acids and had a calculated MW of 39210 Da Multiplesequence alignment of OmpEA with other porins from the Enterobacteriaceae family revealed 51 to 63 identity The first 16 amino acids from the Nterminal exhibited the highest identity 100 to the porins OmpC OmpF and PhoE of Escherichia coli Two methods were used to predict the secondary structure APSSP2 and Hidden and Markov’s model The monomers of OmpEA porin presented a topology of 16 transmembranal βstrands The area of the loops between the β strands was proposed It is suggested that further research on the porin and its loops may be important for understanding the mechanism of E amylovor to invade plant tissues
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