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The process of folding is a seminal event in the life of a protein, as it is essential for proper protein function and therefore cell physiology. Inappropriate folding, or misfolding, can not only lead to loss of function, but also to the formation of protein aggregates, an insoluble association of polypeptides that harm cell physiology, either by themselves or in the process of formation. Several biological processes have evolved to prevent and eliminate the existence of non-functional and amyloidogenic aggregates, as they are associated with several human pathologies. Molecular chaperones and heat shock proteins are specialized in controlling the quality of the proteins in the cell, specifically by aiding proper folding, and dissolution and clearance of already formed protein aggregates. The latter is a function of disaggregases, mainly represented by the ClpB/Hsp104 subfamily of molecular chaperones, that are ubiquitous in all organisms but, surprisingly, have no orthologs in the cytosol of metazoan cells. This review aims to describe the characteristics of disaggregases and to discuss the function of yeast Hsp104, a disaggregase that is also involved in prion propagation and inheritance. O processo de enovelamento é um evento importante para o tempo de vida de uma proteína, uma vez que é essencial para a função adequada da proteína e, por conseguinte, para a fisiologia celular. Enovelamento inadequado, ou mau enovelamento, pode não só conduzir à perda de função, mas também para a formação de agregados de proteína, uma associação insolúvel de polipeptídos que prejudicam a fisiologia celular, quer por si próprios ou no processo de formação. Vários processos biológicos têm evoluído para prevenir e eliminar a existência de agregados não funcionais e amiloidogênicos, uma vez que estão associados com várias patologias humanas. Chaperonas moleculares e proteínas de choque térmico são especializadas no controle de qualidade de proteínas na célula, especificamente, auxiliando o enovelamento correto, dissolução e remoção de agregados de proteína já formados. Esta última é uma função das 'disagregases', representadas principalmente pela subfamília ClpB/ Hsp104 de chaperonas moleculares, que são comuns em todos os organismos, mas, surpreendentemente, não possuem ortólogos no citosol de células de metazoários. Esta revisão tem como objetivo descrever as características das disagregases e discutir a função da Hsp104 de levedura, uma disagregase que também está envolvida na propagação e herança de príons.

Lactobacillus sakei is a lactic acid bacterium that is ubiquitous in the food environment and is one of the most important constituents of commercial meat starter cultures. In this study, in vivo expression technology (IVET) was applied to investigate gene expression of L. sakei 23K during meat fermentation. The IVET vector used (pEH100) contained promoterless and transcriptionally fused reporter genes mediating β-glucuronidase activity and erythromycin resistance. A genomic library of L. sakei 23K was established, and the clones were subjected to fermentation in a raw-sausage model. Fifteen in carne-induced fusions were identified. Several genes encoded proteins which are likely to contribute to stress-related functions. One of these genes was involved in acquisition of ammonia from amino acids, and the remaining either were part of functionally unrelated pathways or encoded hypothetical proteins. The construction and use of isogenic mutants in the sausage model suggested that four genes have an impact on the performance of L. sakei during raw-sausage fermentation. Inactivation of the heat shock regulator gene ctsR resulted in increased growth, whereas knockout of the genes asnA2 , LSA1065, and LSA1194 resulted in attenuated performance compared to the wild-type strain. The results of our study are the first to provide an insight into the transcriptional response of L. sakei when growing in the meat environment. In addition, this study establishes a molecular basis which allows investigation of bacterial properties that are likely to contribute to the ecological performance of the organism and to influence the final outcome of sausage fermentation.