Molecular chaperone function of three small heat-shock proteins from a model probiotic species

Abstract

Small heat-shock proteins (sHSP) are ubiquitous ATP-independent chaperones that prevent irreversible aggregation of heat-damaged denaturing proteins. Lactiplantibacillus plantarum is a widespread Gram-positive bacterium with probiotic claims and vast potential for agro-food, biotechnological and biomedical applications. L. plantarum possesses a family of three sHSP, which were previously demonstrated to be involved in its stress tolerance mechanisms. Here, the three L. plantarum sHSP were heterologously expressed, purified and shown to have a chaperone activity in vitro, measuring their capacity to suppress protein aggregation, as assayed spectrophotometrically by light scattering. Their anti-aggregative capacity was found to be differently influenced by pH. Differences were also found relative to their holdase function and their capacity to modulate liposome membrane fluidity, suggesting interplays between them and indicating diversified activities. This is the first study assessing the chaperone action of sHSP from a probiotic model. The different roles of the three sHSP can increase L. plantarum’s capabilities to survive the various types of stress characterising the diverse habitats of this highly adaptable species. Reported evidence supports the interest in L. plantarum as one of the model species for bacteria that have three different sHSP-encoding genes in their genomes.

Significant influence of four highly conserved amino-acids in lipochaperon-active sHsps on the structure and functions of the Lo18 protein

“…Stress proteins such as small heat shock proteins (sHSP) are present in almost all organisms. Although they have all been described for their role as molecular chaperones 7 , 27 – 29 , a growing number of studies have shown that some of them also play the role of lipochaperon by acting at the cell membrane level to maintain its integrity 16 , 20 – 24 , 30 – 32 . Few sHSPs have been described as performing both these activities, the mechanisms involved in lipochaperon activity are still very poorly understood.…”

“… 14 , 15 , HSP17 from Synechocystis sp . 16 , 17 , HSP17.8 from Arabidopsis thaliana 18 HSP15.8 and HSP16 from Schizosaccharomyces pombe 19 and HSP18.55 from Lactiplantibacillus plantarum 20 have been described as possessing this second activity.…”

The beauty and complexity of the small heat shock proteins: a report on the proceedings of the fourth workshop on small heat shock proteins

“…The three sHSP modulated liposome membrane fluidity differently, with a clear lipochaperone activity for sHSP2. The different apparent functions of the three sHSPs of L. plantarum may account for the organism’s high adaptability and capacity to tolerate various stress conditions (Rocchetti et al 2023 ).…”

Propiedades probióticas y análisis proteómico de Pediococcus pentosaceus 1101

“…Su estructura se caracteriza por un bajo peso molecular (12-43 kDa) y la presencia de un dominio central de α-cristalina altamente conservado (aproximadamente 100 aminoácidos aminoácidos), sus propiedades chaperonas parecen estar estrechamente relacionadas con su capacidad para formar estructuras cuaternarias oligoméricas de diferentes tamaños que encierran el sustrato desplegado, lo protegen del entorno externo y de la agregación/precipitación [Rocchetti et al, 2022].…”