J. Biol. [5], The basic function, as already mentioned (see: Translocase Definition), is to "catalyse the movement of ions or molecules across membranes or their separation within membranes". Gorbalenya, A. E. & Koonin, E. V. Helicases: amino acid sequence comparisons and structurefunction relationships. Beran R.K., Pyle A.M. The crystal structure of the bipolar RecBCD helicase shows interactions between an accessory protein (RecC) and two SF1 helicases with opposite directionality, the 3 to 5 RecB and the 5 to 3 RecD. J. Biol. Pyle A.M. RNA helicases and remodeling proteins. J. Biochem. Yarranton, G. T., Das, R. H. & Gefter, M. L. Enzyme-catalyzed DNA unwinding. UvrD helicase, unlike Rep helicase, dismantles RecA nucleoprotein filaments in Escherichia coli. Engineering and Modification, Enzyme Bernstein, D. A., Zittel, M. C. & Keck, J. L. High-resolution structure of the E.coli RecQ helicase catalytic core. A fork-clearing role for UvrD. Backbone tracking by the SF2 helicase NPH-II. Domain motions were interpreted based upon aligning all structures to HEL1. Biochemistry 39, 205212 (2000). Most of our knowledge about these enzymes stems from pioneering work on SF2 helicases of viral origins, primarily from work on the NS3 proteins from the Flaviviridae viruses, Dengue Virus and HCV, and NPH-II from Vaccinia Virus. The reaction is designated as a transfer from side 1 to side 2 because the designations in and out, which had previously been used, can be ambiguous. Maluf, N. K., Ali, J. Lestini, R. & Michel, B. UvrD controls the access of recombination proteins to blocked replication forks. Curr. PubMedGoogle Scholar. Kawaoka J., Jankowsky E., Pyle A.M. Xu, H. Q. et al. Whereas the CH domain was once positioned above HEL2, binding of Upf2 repositions the CH domain behind HEL1. 27 January 2021, Receive 12 print issues and online access, Prices may be subject to local taxes which are calculated during checkout. Biol. Biochem. Science 291, 121125 (2001). Crystal structure of T7 gene 4 ring helicase indicates a mechanism for sequential hydrolysis of nucleotides. Translocase is a general term for a protein that assists in moving another molecule, usually across a cell membrane. Ali, J. An inactivated nuclease-like domain in RecC with novel function: implications for evolution. Zhang, X. D. et al. J. Mol. Chem. Biochem. Rather, they reverse their gears (Pyle, 2009). Key Points The superfamily 1 (SF1) and SF2 enzymes are non-hexameric enzymes possessing both helicase and single-stranded DNA (ssDNA) translocase activities, as well as the ability to. FtsK is a double-stranded DNA translocase, a motor that converts the chemical energy of binding and hydrolysing ATP into movement of a DNA substrate. Boxed regions indicate the illustrated portion of the helicase. Chem. Proc. Rheumatol. That is, the serine protease domain is essential for conferring strong binding to the helicase domain, and the helicase domain enhances proteolysis by the protease domain (Beran and Pyle, 2008, Beran et al., 2007). sharing sensitive information, make sure youre on a federal Helicases and nucleic acid translocases are motor proteins that have essential roles in nearly all aspects of nucleic acid metabolism, ranging from DNA replication to chromatin remodelling. Nature Reviews Molecular Cell Biology Translocases (EC 7): A new EC Class [Prepared by Keith Tipton] Six enzyme classes have been recognized since the first Enzyme classification and nomenclature list was first approved by the International Union of Biochemistry in 1961. Ann. It is also a historical term for the protein now called elongation factor G, due to its function in moving the transfer RNA (tRNA) and messenger RNA (mRNA) through the ribosome. Careers, Unable to load your collection due to an error. Inhibition can be partially relieved by the binding of the cofactor Upf2 (orange). 310, 327350 (2001). PubMed The DNA repair helicase UvrD is essential for replication fork reversal in replication mutants. They are usually proteins, though some RNA molecules act as enzymes too. Biol. The Escherichia coli UvrD helicase is essential for Tus removal during recombination-dependent replication restart from Ter sites. Eur. The Escherichia coli DEAD protein DbpA recognizes a small RNA hairpin in 23S rRNA. 6, 967980 (2007). 272, 699715 (1997). 26, 38043814 (2007). ISSN 1471-0080 (online) 92, 29862995 (2007). Luo D., Ding S.C., Vela A., Kohlway A., Lindenbach B.D., Pyle A.M. Results with Upf1 are therefore consistent with the notion that translocases do not turn around to run backward. Bidnenko, V., Lestini, R. & Michel, B. Nat Rev Mol Cell Biol 9, 391401 (2008). High resolution crystal structures of SF1 enzymes in complex with DNA and various nucleotide analogues have led to detailed proposals for ssDNA translocation through 'inch-worm' mechanisms that involve relative movements of two subdomains, the interface of which forms the ATP-binding site. We highlight the examples where the presence or absence of additional cofactors alters enzymatic behavior, thereby providing insight into how the cell may use different strategies to regulate helicase activity in vivo. Trends Biochem. J. Mol. Open Access articles citing this article. The repositioning of the CH domain is likely the structural basis for the functional observation that Upf2 enhances the biochemical properties of Upf1. (A) Similar to HCV NS3, the two RecA-like domains of Upf1 close upon binding ATP. Google Scholar. Linder, P. Dead-box proteins: a family affairactive and passive players in RNP-remodeling. Translocase - an overview | ScienceDirect Topics 325, 913935 (2003). Biol. National Library of Medicine 2. This alternation between strong and weak interactions in response to ATP is likely the structural basis for dsRNA translocation. Cheng, W., Hsieh, J., Brendza, K. M. & Lohman, T. M. E. coli Rep oligomers are required to initiate DNA unwinding in vitro. The reaction is designated as a transfer from "side 1" to "side 2" because the designations "in" and "out", which had previously been used, can be . Additionally, the RecA-like domains close upon binding ATP, and HEL2 establishes additional contacts with the dsRNA backbone. Dumont S., Cheng W., Serebrov V., Beran R.K., Tinoco I., Jr., Pyle A.M., Bustamante C. RNA translocation and unwinding mechanism of HCV NS3 helicase and its coordination by ATP. & Keck, J. L. A central role for SSB in Escherichia coli RecQ DNA helicase function. Chem. Enzyme vs Translocase - What's the difference? | WikiDiff The enzyme classification and nomenclature list was first approved by the International Union of Biochemistry in 1961. Between the CH domain and HEL1 is a domain composed of six antiparallel -strands (Domain 1B), and a stalk domain composed of two -helices. Translocase Introduction - Creative Enzymes Like their DNA-remodeling cousins, the core of RNA translocase enzymes is composed of two RecA-like domains ( / domain; a.k.a. Yoneyama M., Kikuchi M., Matsumoto K., Imaizumi T., Miyagishi M., Taira K., Foy E., Loo Y.M., Gale M., Jr., Akira S. Shared and unique functions of the DExD/H-box helicases RIG-I, MDA5, and LGP2 in antiviral innate immunity. Luo D., Xu T., Hunke C., Gruber G., Vasudevan S.G., Lescar J. HCV NS3 is a bifunctional enzyme that contains a helicase domain, and an appended serine protease domain that is important during early stages of viral protein processing (Raney et al., 2010). Pre-steady-state kinetic methods demonstrate that the TraI monomer is a highly processive helicase in vitro. ADP/ATP translocase 1 is the major AAC in human cells and the archetypal protein of this family. Is there a role for ATP hydrolysis during the presentation of the CARD domains and in signaling? Structure of the hepatitis C virus RNA helicase domain. Upon binding ATP, HEL2i moves further toward the dsRNA and establishes more contacts using this -helix. Singleton, M. R., Dillingham, M. S., Gaudier, M., Kowalczykowski, S. C. & Wigley, D. B. Get the most important science stories of the day, free in your inbox. Translocases biological importance relies primarily on their critical function, in the way that they provide movement across the cell's membrane in many cellular processes that are substantial, such as: The enzyme subclasses designate the types of components that are being transferred, and the sub-subclasses indicate the reaction processes that provide the driving force for the translocation.[12]. Jones D.M., Atoom A.M., Zhang X., Kottilil S., Russell R.S. Lohman, T. M. DNA helicases: dimeric enzyme action (ed. Translocases are the most common secretion system in Gram positive bacteria. However, most translocative and processive enzymes have additional domains that potentiate important roles in substrate recognition and helicase function. Interestingly, through the cycles of ATP binding and hydrolysis, the orientation of Trp501 remains stacked with the nucleobase (Appleby et al., 2011). 6.2C). USA 99, 1600616011 (2002). CAS 43, 335343 (1979). Biol. CARD1 and CARD2 stack upon one another, and CARD2 forms extensive interactions with HEL2i that are stabilized by salt bridges and hydrophobic contacts (Kowalinski et al., 2011) (Fig. (A) Domain motions of HCV NS3 in response to RNA and ATP binding. Further, some helicases, such as E. coli DbpA, use these extra domains to recognize a specific RNA tertiary structure in order to activate its ATPase activity (Tsu et al., 2001), whereas other helicases lacking these additional domains, such as S. cerevisiae Dbp5, require the binding of auxiliary cofactors (Gle1) and small molecules (inositol hexakisphosphate) to stimulate RNA release (Montpetit et al., 2011). Shereda, R. D., Bernstein, D. A. Biochemistry 44, 1299012997 (2005). The authors of this work are supported by a National Institutes of Health (NIH) grant. Microbiol. Yu, J., Ha, T. & Schulten, K. Structure-based model of the stepping motor of PcrA helicase. Transferase | enzyme | Britannica J. Mol. The acceptor then re-emits the energy with a different, longer wavelength that is characteristic of the acceptor fluorophore. [14] Based on the reaction they are linked to, EC 7.1 can be further classified into: An important translocase contained in this group is ATP synthase, also known as EC 7.1.2.2. 33, 14561459 (2005). This is a surprising finding, given that one would expect that a helicase that translocates and unwinds with an opposite polarity as NS3 to position itself on the RNA in a reversed orientation. 27 May 2022, Nature Communications Chem. 22, 49104921 (2003). Nature 423, 893897 (2003). 282, 2707627085 (2007). Biochemistry 41, 643651 (2002). The robust unwinding activities of NS3 and NPH-II enzymes have helped reveal the specific structural and chemical features of RNA that are important for translocation and unwinding. Interestingly, maximal translocation activity was observed using triphosphorylated duplex RNA, thereby highlighting the specific structural and chemical features of the nucleic acid substrate requirement for RIG-I. These enzymes catalyze the movement of ions or molecules across membranes or their separation within membranes. J. Biochem. Bernstein E., Caudy A.A., Hammond S.M., Hannon G.J. It comprises the membrane proteins SecYEG(DFYajC) and the peripheral ATPase SecA, which acts as a motor subunit. Zhang, W. et al. Kang D.C., Gopalkrishnan R.V., Wu Q., Jankowsky E., Pyle A.M., Fisher P.B. A cruciform DNA structure that is generated during the synaptic phase of homologous recombination. ATP binds in the cleft formed between these two domains and conserved amino acid motifs responsible for ATP binding and hydrolysis line up along each RecA-like domain facing inward toward the cleft. However, unwinding is likely achieved by the steric pressure from a -hairpin that projects from HEL2. Dev. Hill, T. L. & Tsuchiya, T. Theoretical aspects of translocation on DNA: Adenosine triphosphatase and treadmilling binding proteins. Biol. The CARD domain: a new apoptotic signalling motif.
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