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AAA+ proteins form asymmetric hexameric rings that hydrolyze ATP and thread substrate proteins through a central channel via mobile substrate-binding pore loops. Understanding how ATPase and threading activities are regulated and intertwined is key to understanding the AAA+ protein mechanism. We studied the disaggregase ClpB, which contains tandem ATPase domains (AAA1, AAA2) and shifts between low and high ATPase and threading activities. Coiled-coil M-domains repress ClpB activity by encircling the AAA1 ring. Here, we determine the mechanism of ClpB activation by comparing ATPase mechanisms and cryo-EM structures of ClpB wild-type and a constitutively active ClpB M-domain mutant. We show that ClpB activation reduces ATPase cooperativity and induces a sequential mode of ATP hydrolysis in the AAA2 ring, the main ATPase motor. AAA1 and AAA2 rings do not work synchronously but in alternating cycles. This ensures high grip, enabling substrate threading via a processive, rope-climbing mechanism.
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http://dx.doi.org/10.1016/j.celrep.2019.05.075 | DOI Listing |
Microbiol Spectr
August 2025
Liaoning Key Laboratory of Marine Animal Immunology & Disease Control, Dalian Ocean University, Dalian, China.
With the continuous expansion of oyster farming scale, disease has become one of the main obstacles to restricting the development of oyster farming. In the present study, 20 bacterial strains were identified from with pustulosis, among which emerged as the predominant strain, characterized by its rod-shaped morphology and possession of flagella. exhibited α-hemolytic activity at 28°C and displayed high susceptibility to all 20 chemotherapeutic agents tested.
View Article and Find Full Text PDFJ Hazard Mater
August 2025
National Key Laboratory of Veterinary Public Health and Security, College of Veterinary Medicine, China Agricultural University, Beijing, China. Electronic address:
Methicillin-resistant Staphylococcus aureus (MRSA) represents a significant public health concern owing to its formidable antibiotic resistance and robust capacity for biofilm formation. The cross-adaptation mechanism enables MRSA to develop tolerance to environmental stressors such as antibiotics, acid, heat and osmotic pressure, leading to the persistence infections and environmental contamination. The cross-adaptation mechanism enables MRSA to develop tolerance to environmental stressors, such as antibiotics, acid, heat and osmotic pressure, leading to the persistence infections and environmental contamination.
View Article and Find Full Text PDFMicrobiol Spectr
June 2025
Division of Environmental Health Sciences, School of Public Health, University of Minnesota, Minneapolis, Minnesota, USA.
is a leading cause of foodborne infections worldwide and primarily transmitted to humans through the consumption of contaminated poultry meat. To enhance -associated food safety, it is critical to understand how survives during the thermal processing of poultry products. In this study, we monitored the survival of 86 .
View Article and Find Full Text PDFProc Natl Acad Sci U S A
February 2025
Laboratory of Molecular Biology, National Cancer Institute, NIH, Bethesda, MD 20892.
Hsp70, Hsp90, and ClpB/Hsp100 are molecular chaperones that help regulate proteostasis. Bacterial and yeast Hsp70s and their cochaperones function synergistically with Hsp90s to reactivate inactive and aggregated proteins by a mechanism that requires a direct interaction between Hsp90 and Hsp70 both in vitro and in vivo. and yeast Hsp70s also collaborate in bichaperone systems with ClpB and Hsp104, respectively, to disaggregate and reactivate aggregated proteins and amyloids such as prions.
View Article and Find Full Text PDFFront Pharmacol
December 2024
School of Basic Medicine, Guizhou University of Traditional Chinese Medicine, Guiyang, Guizhou, China.
Introduction: The mechanism of tannic acid (TA) intervention on methicillin-resistant (MRSA, USA 300) biofilm formation was explored using proteomics.
Methods: The minimum inhibitory concentration (MIC) of TA against the MRSA standard strain USA 300 was determined by two-fold serial dilution of the microbroth. The effects of TA were studied using crystal violet staining.