Repurposing Hsp104 to Antagonize Seminal Amyloid and Counter HIV Infection

Abstract

Naturally occurring proteolytic fragments of prostatic acid phosphatase (PAP248-286 and PAP85-120) and semenogelins (SEM1 and 2) form amyloid fibrils in seminal fluid, which capture HIV virions and promote infection. For example, PAP248-286 fibrils, termed SEVI (Semen derived Enhancer of Viral Infection), can potentiate HIV infection by several orders of magnitude. Here, we design three disruptive technologies to rapidly antagonize seminal amyloid by repurposing Hsp104, an amyloid-remodeling nanomachine from yeast. First, Hsp104 and an enhanced engineered variant, Hsp104A503V, directly remodel SEVI and PAP85-120 fibrils into non-amyloid forms. Second, we elucidate catalytically inactive Hsp104 scaffolds that do not remodel amyloid structure, but cluster SEVI, PAP85-120, and SEM1(45-107) fibrils into larger assemblies. Third, we modify Hsp104 to interact with the chambered protease ClpP, which enables coupled remodeling and degradation to irreversibly clear SEVI and PAP85-120 fibrils. Each strategy diminished the ability of seminal amyloid to promote HIV infection and could have therapeutic utility.

Chaperones as Suppressors of Protein Misfolded Oligomer Toxicity

“…This activity was carried out in the absence of ATP, indicating therefore that secHsp70 exploits its holdase function to interact with the oligomers in the absence of detectable clustering (Fernandez-Funez et al, 2016). It is interesting to note that other Hsps that were found able to interact with aggregates, such as Hsp104 (Arimon et al, 2008; Castellano et al, 2015), Hsp70 (Mannini et al, 2012) and Ssa1p (Xu L. et al, 2013), exert the capacity to bind to the aggregates without consumption of ATP.…”

Mechanistic Insights into Hsp104 Potentiation

“…Potentiating mutations in the MD obviate any absolute requirement for Hsp70 in disaggregation of amorphous aggregates and typically (under physiological salt conditions) enhance Hsp104 ATPase activity (62,67). Potentiated Hsp104 variants also display accelerated substrate translocation, enhanced unfoldase activity, and enhanced amyloid-remodeling activity (45,62). They can also recognize shorter unfolded tracts in client proteins compared with Hsp104 (63).…”

“…Remarkably, Hsp104 can remodel amyloid substrates alone, without the aid of any other chaperones (22,24,26,31,33,45,(53)(54)(55)(56). However, to disaggregate amorphous protein aggregates, Hsp104 usually needs to collaborate with the Hsp110, Hsp70, and Hsp40 chaperone system (23,26,30,32,57).…”

Remodeling Amyloid Fibers: Baker’s Yeast Shows Us the Way

“…To prevent the damaging effects of protein misfolding, cells have evolved various endogenous mechanisms such as chaperone pathways to ensure proper and rapid folding of nascent polypeptide chains and degradation of improperly folded proteins (Brandvold and Morimoto, 2015). The paper by Castellano and coworkers presents a novel approach in the use of a modified, yeast-specific chaperone Hsp104 as a possible therapeutic to remodel amyloids in semen and reduce HIV infectivity and transmission (Castellano et al, 2015). Hsp104 is a disaggregase involved in the recovery after stress-induced protein aggregation in S. cerevisiae and the only cellular component known to remodel amyloid fibrils (Glover and Lindquist, 1998).…”

“…Wellknown examples of proteopathies are Alzheimer's and Parkinson's disease, which are both linked to amyloid fibril formation. In this issue of Chemistry & Biology, Castellano et al (2015) describe the way to harness the power of a protein from baker's yeast, Hsp104, to disaggregate the fibrils.…”