RESUMO
The primary 2A/2B polyprotein cleavage of aphtho-and cardioviruses is mediated by their 2A proteins cleaving C-terminally. Whilst the aphthovirus 2A region is only 16 aa (possibly 18 aa) long, the cardiovirus 2A protein is some 150 aa. We have previously shown that foot-and-mouth disease virus (FMDV) 2A is able to mediate cleavage in an artificial (chloramphenicol acetyltransferase/FMDV 2A/beta-glucuronidase [CAT-2A-GUS]) polyprotein system devoid of any other FMDV sequences with high (approximately 85%), although not complete, cleavage. In this paper we show that insertion of upstream FMDV capsid protein 1 D sequences increases the activity. In addition, we have demonstrated that the cardiovirus Theiler's murine encephalomyelitis virus(TME) 2A protein, when linked to GUS in a single ORF, is able to cleave at its own C terminus with high efficiency--if not completely. The C-terminal 19 aa of TME 2A, together with the N-terminal proline residue of protein 2B, were inserted into the CAT/GUS artificial polyprotein system (in a single ORF). This recombinant [CAT-deltaTME2A-GUS] polyprotein was able to mediate cleavage with high (approximately 85%) efficiency--directly comparable to the activity observed when FMDV 2A was inserted. A similar insertion into [CAT-GUS] of the C-terminal 19 aa of the cardiovirus encephalomyocarditis virus (EMC) 2A, together with the N-terminal proline residue of protein 2B, produced a [CAT-delta EMC2A-GUS] polyprotein which also mediated cleavage at approximately 85%. Analysis of the products of expression of these artificial polyproteins in a prokaryotic translation system did not, apparently, reveal any GUS cleavage product.
Assuntos
Aphthovirus/metabolismo , Proteínas Virais/metabolismo , Sequência de Aminoácidos , Animais , Sequência de Bases , Cardiovirus/metabolismo , Cloranfenicol O-Acetiltransferase/biossíntese , Primers do DNA , Dados de Sequência Molecular , Plasmídeos , Reação em Cadeia da Polimerase , Biossíntese de Proteínas , Coelhos , Proteínas Recombinantes de Fusão/biossíntese , Reticulócitos/metabolismo , Homologia de Sequência de Aminoácidos , Transcrição Gênica , Proteínas Virais/biossíntese , Proteínas Virais/químicaRESUMO
Geriatric assessment and treatment units provide a multidisciplinary approach to managing a targeted group of frail seniors who are hard to care for in traditional systems. They are also important teaching and research centers for geriatrics.This article describes, as an example, the Short Term Assessment and Treatment Unit at Vancouver General Hospital.
