Disruption of the Crithidia fasciculata KAP1 gene results in structural rearrangement of the kinetoplast disc

The mitochondrial DNA (kinetoplast DNA) in trypanosomatids exists as a high ly organized nucleoprotein structure with the DNA consisting of thousands o f interlocked circles. Four H1 histone-like proteins (KAP1, 2, 3 and 4) are associated with the kinetoplast DNA in the trypanosomatid Crithidia fascic ulata. We have disrupted both alleles of the KAP1 gene in this diploid prot ozoan and shown that expression of the KAP1 protein is eliminated. The muta nt strain is viable but has substantial rearrangement of the kinetoplast st ructure. Expression of the KAP1 protein from an episome restored expression of the KAP1 protein in the mutant strain and also restored a normal kineto plast structure. These studies provide evidence that the KAP1 protein is in volved in kinetoplast DNA organization in vivo but is nonessential for cell viability. (C) 2001 Elsevier Science B.V. All rights reserved.