The positions of the sigma-factor genes, whiG and sigF, in the hierarchy controlling the development of spore chains in the aerial hyphae of Streptomyces coelicolor A3(2) |
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Authors: | Gabriella H Kelemen Gary L Brown Ján Kormanec Laura Potúkova Keith F Chater Mark J Buttner |
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Institution: | Department of Cell and Molecular Biology, UmeåUniversity, S 901 87 Umeå, Sweden. |
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Abstract: | Multiple yop mutant strains of Yersinia pseudotuberculosis not expressing several virulence effector Yop proteins (YopH, M, E, K and YpkA) were engineered. When high-copy-number plasmids carrying the ypkA or the yopE gene with their endogenous promoters were introduced into the engineered strains, the corresponding Yop protein was secreted at high levels in vitro . These multiple yop mutant strains, when harbouring the yopE gene in trans , behaved as the wild-type strain with respect to YopB-dependent translocation of YopE through the HeLa cell plasma membrane. Using these multiple yop mutant strains, it was demonstrated that the YpkA Ser/Thr protein kinase mediates morphological alterations of infected cultured HeLa cells different from those mediated by YopE and YopH. Furthermore, YpkA is shown to be translocated by a YopB-dependent translocation mechanism from surface-located bacteria and subsequently targeted to the inner surface of the target-cell plasma membrane. The pattern of YpkA localization after infection suggests that this Yop effector is involved in interference with signal transduction. |
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