Protist News

Beat Blum Memoriam

Kinetoplast DNA – Minicircles and Maxicircles

Trypanosome and Leishmania parasites contain a mass of DNA situated in the matrix of the single mitochondrion adjacent to the basal body of the flagellum. This DNA consists of around 10,000 catenated 900 bp minicircles in Leishmania and 20–50 24 kb maxicircles. This mitochondrial DNA is known as the “kDNA network”. My laboratory has been working on this unusual mitochondrial DNA my entire career at UCLA. Isolation of RNA from purified kinetoplast-mitochondria led to the discovery by Agda da

RNA Editing Discovery

In 1986 Rob Benne in the University of Amsterdam published an at first controversial paper showing that the transcript of the cytochrome oxidase subunit II or CO2 gene contained four extra non-encoded uridine (U) residues, which overcame an encoded frameshift and would allow translation of the CO2 protein. Benne coined the term, “RNA editing”, to indicate this then mysterious process. In 1988, we, in collaboration with the Stuart lab, showed that Benne was indeed correct and the cytochrome b

Beat Blum and the Discovery of gRNAs

Beat Blum arrived in my lab in 1989 to begin a postdoctorate fellowship. Beat kept very clear and complete notebooks – labeled “Labor Journals” in his Swiss German. He always first laid out the problem to be solved and then suggested in his notebook several experimental approaches.

At that time we had the genomic or “pre-edited” maxicircle sequences of multiple “cryptogenes”. The edited sequences were obtained by doing PCR on total kRNA using a 3′ primer with or without edited sequence and a 5′

Model for Editing

Beat Blum worked in my lab at an exciting period and he was one of the main reasons for the excitement. The discovery of a new class of small maxicircle- and minicircle-encoded RNAs that contain the sequence information for determining the sites and numbers of U’s inserted or deleted by base-pairing was novel and led directly to the proposal of a mechanism for kinetoplastid RNA editing. Beat, however, then had the idea that the inserted U’s possibly came from the 3′ oligo U tails of the gRNAs

Selected Publications

Blum B, Bakalara N, Simpson L (1990) A model for RNA editing in kinetoplastid mitochondria: “Guide RNA” molecules transcribed from maxicircle DNA provide the edited information. Cell 60:189–198

Blum B, Simpson L (1990) Guide RNAs in kinetoplastid mitochondria have a non-encoded 3′ oligo(U) tail involved in recognition of the preedited region. Cell 62:391–397

Sturm NR, Maslov DA, Blum B, Simpson L (1992) Generation of unexpected editing patterns in Leishmania tarentolae mitochondrial mRNAs: