STRUCTURE, ORGANIZATION AND PUTATIVE FUNCTION OF THE GENES IDENTIFIEDWITHIN A 23.9-KB FRAGMENT FROM ARABIDOPSIS-THALIANA CHROMOSOME-IV

In the framework of the complete genome sequencing programme of the cr ucifer Arabidopsis thaliana, a 23.9-kb fragment from the long arm of c hromosome IV has been analysed. This paper presents a methodological a pproach, integrating computerized predictions? database screening, the sequencing of cognate cDNAs and a PCR-based detection of expression t hat allows the accumulation of an important amount of information from an anonymous sequence. This work revealed the organization of novel g enes and the vestige of a copia-like retrotransposon. The gene AtRH1 e ncodes the first member of a new subfamily of the plant DEAD box RNA h elicases. A recurrent and complete search of dbEST has been used to ev aluate the number of different RNA helicases expressed in A. thaliana. On the 18 discriminated members of the family, only a small number se ems to be expressed at a relatively high level. The putative gene AtTS 1 encodes a novel terpene synthase in A. thaliana, and the genes G1458 7-5 and G14587-6 encode unknown proteins. This study illustrates most of the situations that could be encountered during the analysis of an anonymous sequence from A. thaliana. (C) 1997 Elsevier Science B.V.