ATP-dependent proteases in the chloroplast
2008 (English)In: ATP-dependent Proteases in the Plant Chloroplast / [ed] Eva Kutejová, Kerala, India: Research Signpost , 2008, 145-176 p.Chapter in book (Refereed)
Systematic comparative analysis of the available sequenced genomes of model organisms has led to the identification of an increasing number of protease genes. ATP-dependent proteases are one of the largest groups of proteolytic enzymes found across all kingdoms of life and are associated to several essential physiological pathways. FtsH-, Clp-, and Lon-like proteases, all derived from bacterial ancestors, also have been identified in the plant chloroplast, where they form multi-subunit complexes consisting of different gene products. Recent studies in model organisms like the annual plant Arabidopsis thaliana or the photosynthetic cyanobacterium Synechocystis sp. PCC 6803 have identified substrates and functions of these isomers. Although only a limited number of proteases has been identified by biochemical methods, novel protease homologous that are targeted to plastids have been predicted. This review covers the current knowledge on ATP-dependent proteases in the chloroplast.
Place, publisher, year, edition, pages
Kerala, India: Research Signpost , 2008. 145-176 p.
IdentifiersURN: urn:nbn:se:umu:diva-11494ISBN: 978-81-308-0282-4OAI: oai:DiVA.org:umu-11494DiVA: diva2:151165
Introduction - ATP-dependent proteases constitute a unique proteolytic system. Although proteolysis is an exergonic process, these proteases require energy derived from ATP hydrolysis in order to function. This energy requirement is closely related to their structures and mechanisms of action. Their proteolytic active sites are usually sequestered in barrel-like structures that prevent uncontrolled proteolysis. These ring shaped proteolytic domains, or proteolytic sub-complexes, are connected to and cooperate with structurally similar ATPase domains or ATPase sub-complexes. Substrates bind to these ATPase domains or ATPase sub-complexes and the energy released by ATP hydrolysis is used to unfold and translocate the substrate into the proteolytic cavity and to activate the proteases themselves. ATP-dependent proteases are present in all prokaryotic and eukaryotic cells. In eukaryotic cells, they are localized in the cytosol and in the nucleus (proteasome) as well as in the organelles: mitochondria, chloroplasts and peroxisomes (Lon, Clp proteases, FtsH, HslUV). They are responsible for the degradation of damaged or misassembled proteins and of non-assembled protein subunits that might be harmful to the cells. ATP-dependent proteases also help control the concentration of several regulatory proteins. In prokaryotes, they are involved in stress response, pathogenicity, cell signaling and development. In eukaryotes, they are important for the proper functioning of organelles and for the immune and stress responses. Deficiencies in ATP-dependent proteases are connected with such severe disorders as dystrophies, neurodegenerative diseases and cancer and are thought to affect aging as well. ATP-dependent proteases are thus important for the biogenesis and homeostasis of living organisms. In this book, we focus on a particular group of ATP-dependent proteases (Lon, Clp proteases, FtsH and HslUV) that function in both prokaryotes and in the organelles of eukaryotes. We discuss the biological, biochemical, structural and evolutionary aspects of this important group of proteases. We do not describe the structure and function of the proteasomes, since they represent highly complex systems and would require a separate volume. We hope you enjoy reading our book!2009-01-132009-01-132011-12-01Bibliographically approved