Identification and partial characterization of two chloroplast-encoded potential RNA metabolism genes roaA and mat1

Abstract

Although group I and group II introns are capable of self-splicing in vitro, there is growing evidence that trans acting factors facilitate splicing of group I and group II introns in vivo. For group II introns, these trans acting factors include maturases and RNA chaperones. Maturases are intron-encoded enzymes which splice the intron which encodes them and in some cases mobilize the intron. RNA chaperones are a group of general RNA binding proteins which facilitate formation of correctly folded catalytic RNAs. The Euglena gracilis chloroplast genome is an ideal system in which to study RNA metabolism, especially splicing. The genome is composed of 38% introns, including group II, group III and twintrons. Although Euglena gracilis chloroplast pre-mRNAs must undergo extensive processing and splicing before they are translated, no chloroplast encoded maturases or RNA chaperones have been described. I have characterized two potential RNA metabolism genes. The roaA gene is unique to the Euglena chloroplast and encodes a potential general RNA binding protein. The roaA gene and mRNA are defined in this dissertation. The roaA protein product and the protein product of a potential maturase, mat1, have also been identified. Identification of these two protein products lays the groundwork for future studies regarding the role of these two proteins in chloroplast RNA metabolism.