This Article Full Text Full Text (PDF) All Versions of this Article: 16/8/2233    most recent tpc.104.022657v1 Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (7) Citing Articles via Google Scholar Google Scholar Articles by Bortfeld, M. Articles by Basse, C. W. Search for Related Content PubMed PubMed Citation Articles by Bortfeld, M. Articles by Basse, C. W. Agricola Articles by Bortfeld, M. Articles by Basse, C. W.

The Ustilago maydis a2 Mating-Type Locus Genes lga2 and rga2 Compromise Pathogenicity in the Absence of the Mitochondrial p32 Family Protein Mrb1

Max-Planck-Institut für Terrestrische Mikrobiologie, Abteilung Organismische Interaktionen, 35043 Marburg, Germany

³ To whom correspondence should be addressed. E-mail basse{at}staff.uni-marburg.de; fax 49-6421-178609.

The Ustilago maydis mrb1 gene specifies a mitochondrial matrix protein with significant similarity to mitochondrial p32 family proteins known from human and many other eukaryotic species. Compatible mrb1 mutant strains were able to mate and form dikaryotic hyphae; however, proliferation within infected tissue and the ability to induce tumor development of infected maize (Zea mays) plants were drastically impaired. Surprisingly, manifestation of the mrb1 mutant phenotype selectively depended on the a2 mating type locus. The a2 locus contains, in addition to pheromone signaling components, the genes lga2 and rga2 of unknown function. Deletion of lga2 in an a2mrb1 strain fully restored pathogenicity, whereas pathogenicity was partially regained in an a2mrb1rga2 strain, implicating a concerted action between Lga2 and Rga2 in compromising pathogenicity in mrb1 strains. Lga2 and Rga2 localized to mitochondria and Mrb1 interacted with Rga2 in the yeast two-hybrid system. Conditional expression of lga2 in haploid cells reduced vegetative growth, conferred mitochondrial fragmentation and mitochondrial DNA degradation, and interfered with respiratory activity. The consequences of lga2 overexpression depended on the expression strength and were greatly exacerbated in mrb1 mutants. We propose that Lga2 interferes with mitochondrial fusion and that Mrb1 controls this activity, emphasizing a critical link between mitochondrial morphology and pathogenicity.

This article has been cited by other articles:

				L. Molina and R. Kahmann An Ustilago maydis Gene Involved in H2O2 Detoxification Is Required for Virulence PLANT CELL, July 1, 2007; 19(7): 2293 - 2309. [Abstract] [Full Text] [PDF]

				M. Scherer, K. Heimel, V. Starke, and J. Kamper The Clp1 Protein Is Required for Clamp Formation and Pathogenic Development of Ustilago maydis PLANT CELL, September 1, 2006; 18(9): 2388 - 2401. [Abstract] [Full Text] [PDF]

				J. Schirawski, B. Heinze, M. Wagenknecht, and R. Kahmann Mating Type Loci of Sporisorium reilianum: Novel Pattern with Three a and Multiple b Specificities Eukaryot. Cell, August 1, 2005; 4(8): 1317 - 1327. [Abstract] [Full Text] [PDF]

				C. W. Basse Dissecting Defense-Related and Developmental Transcriptional Responses of Maize during Ustilago maydis Infection and Subsequent Tumor Formation Plant Physiology, July 1, 2005; 138(3): 1774 - 1784. [Abstract] [Full Text] [PDF]