Translation of Some Maize Small Heat Shock Proteins Is Initiated From Internal In-Frame AUGs

Abstract

Etiolated maize radicles (inbred Oh43) subjected to a brief heat shock synthesize a family of small heat shock proteins (≃18 kD) that is composed of at least 12 members. We previously described the cDNA-derived sequence of three maize shsp mRNAs (cMHSP18-1, cMHSP18-3, and cMHSP18-9). In this report, we demonstrate that the mRNA transcribed in vitro from one of these cDNAs (cMHSP 18-9) is responsible for the synthesis of three members of the shsp family, and we suggest that cMHSP18-3 may be responsible for the synthesis of three additional members and cMHSP18-1 for the synthesis of two other members of this family. The fact that these genes do not contain introns, coupled with the observations reported herein, suggest that maize may have established another method of using a single gene to produce a number of different proteins.

Induction of a cDNA clone from rice encoding a class II small heat shock protein by heat stress, mechanical injury, and salicylic acid

“…Frappier et al [47] demonstrated that in vitro transcription of the mRNA from the cDNA clone cMHSP18-9 is responsible for the synthesis of three members of the sHSP family in maize and suggested that cMHSP18-3 and cMHSP18-1 may be responsible for the synthesis of five additional members of this family. They further suggested that in maize a single gene might produce a number of different proteins [47]. Although we obtained several deletion clones some of which even encoded shorter peptides with the same open reading frame as Oshsp18.0-CII, our Oshsp18.0-CII has only one protein product (Fig.…”