Functional analysis of promoters of genes encoding components of the plant mitochondrial respiratory chain.

WELCHEN, ELINA.; CHAN, RAQUEL L.; GONZALEZ, DANIEL H.

Villa Carlos Paz, Córdoba

Congreso; XXXVIII Reunión anual de la Sociedad Argentina de Investigaciones en Bioquímica y Biología Molecular (SAIB).; 2002

FUNCTIONAL ANALYSIS OF PROMOTERS OF GENES ENCODING COMPONENTS OF THE PLANT MITOCHONDRIAL RESPIRATORY CHAIN Studies from our laboratory have determined that the expression of genes encoding components of the final portion of the plant mitochondrial respiratory chain is modulated by cell-specific and metabolic factors. To gain insight into the mechanisms involved in regulation, we are analyzing the promoters of some of these genes from Arabidopsis thaliana. We have constructed fusions of different regions of the promoters of genes encoding cytochrome c (cytc-1) and cytochrome c oxidase subunit 5b (cox5b-1) to the gus reporter gene and introduced them stably into Arabidopsis. The corresponding promoters directed expression of the reporter gene mainly in anthers. For the cytc-1 gene, a 425 bp promoter fragment (from –296 to +129) was enough to confer preferential expression in anthers, while a further deletion down to –91 abolished this behavior. The smaller construct conserved, however, responses to metabolites. For the cox5b-1 gene, a 394 bp fragment was enough to confer cell-type and metabolite-dependent responses. The experiments with transgenic plants were complemented with electrophoretic mobility shift assays of DNA binding activities present in plant extracts prepared from different sources. A correlation between increased expression and the appearance of shifted bands was observed. Studies are underway to further define the promoter fragments and proteins involved in these responses.