The translational apparatus of Tortula ruralis: polysomal retention of transcripts encoding the ribosomal proteins RPS14, RPS16 and RPL23 in desiccated and rehydrated gametophytes

• Published in: Journal of experimental botany 2000-10, Vol.51 (351), p.1655-1662
• Main Authors: Wood, Andrew J., Joel Duff, R., Oliver, Melvin J.
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Biological and medical sciences; Bryopsida - genetics; Cell and Molecular Biology, Biochemistry and Molecular Physiology; Cell biochemistry; Cell physiology; Complementary DNA; Desiccation; EST; expressed sequence tag; Fundamental and applied biological sciences. Psychology; Gametophytes; Messenger RNA; Molecular and cellular biology; Molecular genetics; Molecular Sequence Data; moss; Mosses; open reading frame; Oral rehydration; ORF; Phylogeny; Plant physiology; Plant physiology and development; Plants; Protein Biosynthesis; ribosomal protein; Ribosomal proteins; Ribosomal Proteins - chemistry; Ribosomal Proteins - genetics; Ribosomes; RNA; RNA, Messenger - genetics; RNA, Messenger - metabolism; RPL23 protein; RPS14 protein; RPS16 protein; Sequence Homology, Amino Acid; Tortula ruralis; translation; Translation. Translation factors. Protein processing
• ISSN: 0022-0957; 1460-2431
• DOI: 10.1093/jexbot/51.351.1655

Tortula ruralis (Syntrichia ruralis) is an important model system for the study of plant vegetative desiccation tolerance. One of the most intriguing aspects of desiccation-tolerant plants is the maintenance of key cellular components in stable and viable forms in the desiccated state, particularly those related to the translational apparatus (i.e. ribosomes and ribosomal RNAs). This study investigated the third integral component of the translational apparatus, the ribosomal proteins. Three T. ruralis cDNAs encoding predicted polypeptides with significant similarity to ribosomal proteins were isolated from a cDNA expression library derived from the polysomal, messenger ribonucleoprotein particle (mRNP) fraction of desiccated gametophytes; Rps14 and Rps16 encode the small‐subunit ribosomal proteins RPS14 and RPS16, respectively, and Rpl23 encodes the large‐subunit ribosomal protein RPL23. RPS14, RPS16 and RPL23, the deduced polypeptides, have predicted molecular masses of 14.4 kDa, 16.2 kDa and 14.9 kDa and predicted pI's of 11.08, 10.34 and 10.67, respectively. Phylogenetic analysis of the deduced amino acid sequences demonstrated that each of the T. ruralis proteins is most similar to ribosomal proteins from higher plants even though RPS14 and RPL23 show high divergence from their other plant counterparts. RNA blot hybridizations of RNAs present within the polysomal mRNP fraction (i.e. the 100 K×g pellet) demonstrated that Rps14, Rps16 and Rpl23 are expressed in moss gametophytes during a desiccation–rehydration cycle and, according to the prior cDNA classification scheme in T. ruralis, are constitutive clones. These findings clearly demonstrated that Rps14, Rps16 and Rpl23 transcripts are retained within the polysomal fractions of desiccated gametophytes.