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Moretto, Luisa
Publications (2 of 2) Show all publications
Moretto, L., Heylen, R., Holroyd, N., Vance, S. & Broadhurst, R. W. (2019). Modular type I polyketide synthase acyl carrier protein domains share a common N-terminally extended fold. Scientific Reports, 9, Article ID 2325.
Open this publication in new window or tab >>Modular type I polyketide synthase acyl carrier protein domains share a common N-terminally extended fold
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2019 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 9, article id 2325Article in journal (Refereed) Published
Abstract [en]

Acyl carrier protein (ACP) domains act as interaction hubs within modular polyketide synthase (PKS) systems, employing specific protein-protein interactions to present acyl substrates to a series of enzyme active sites. Many domains from the multimodular PKS that generates the toxin mycolactone display an unusually high degree of sequence similarity, implying that the few sites which vary may do so for functional reasons. When domain boundaries based on prior studies were used to prepare two isolated ACP segments from this system for studies of their interaction properties, one fragment adopted the expected tertiary structure, but the other failed to fold, despite sharing a sequence identity of 49%. Secondary structure prediction uncovered a previously undetected helical region (H0) that precedes the canonical helix-bundle ACP topology in both cases. This article reports the NMR solution structures of two N-terminally extended mycolactone mACP constructs, mH0ACPa and mH0ACPb, both of which possess an additional alpha-helix that behaves like a rigid component of the domain. The interactions of these species with a phosphopantetheinyl transferase and a ketoreductase domain are unaffected by the presence of H0, but a shorter construct that lacks the H0 region is shown to be substantially less thermostable than mH0ACPb. Bioinformatics analysis suggests that the extended H0-ACP motif is present in 98% of type I cis-acyltransferase PKS chain-extension modules. The polypeptide linker that connects an H0-ACP motif to the preceding domain must therefore be similar to 12 residues shorter than previously thought, imposing strict limits on ACP-mediated substrate delivery within and between PKS modules.

Place, publisher, year, edition, pages
Nature Publishing Group, 2019
National Category
Biochemistry and Molecular Biology
Research subject
Chemistry, Biochemistry
Identifiers
urn:nbn:se:lnu:diva-81092 (URN)10.1038/s41598-019-38747-9 (DOI)000459094800006 ()30787330 (PubMedID)2-s2.0-85061808062 (Scopus ID)
Available from: 2019-03-15 Created: 2019-03-15 Last updated: 2019-08-29Bibliographically approved
Månsson, A., Ušaj, M., Moretto, L. & Rassier, D. E. (2018). Do Actomyosin Single-Molecule Mechanics Data Predict Mechanics of Contracting Muscle?. International Journal of Molecular Sciences, 19(7), Article ID 1863.
Open this publication in new window or tab >>Do Actomyosin Single-Molecule Mechanics Data Predict Mechanics of Contracting Muscle?
2018 (English)In: International Journal of Molecular Sciences, ISSN 1422-0067, E-ISSN 1422-0067, Vol. 19, no 7, article id 1863Article, review/survey (Refereed) Published
Abstract [en]

In muscle, but not in single-molecule mechanics studies, actin, myosin and accessory proteins are incorporated into a highly ordered myofilament lattice. In view of this difference we compare results from single-molecule studies and muscle mechanics and analyze to what degree data from the two types of studies agree with each other. There is reasonable correspondence in estimates of the cross-bridge power-stroke distance (7-13 nm), cross-bridge stiffness (similar to 2 pN/nm) and average isometric force per cross-bridge (6-9 pN). Furthermore, models defined on the basis of single-molecule mechanics and solution biochemistry give good fits to experimental data from muscle. This suggests that the ordered myofilament lattice, accessory proteins and emergent effects of the sarcomere organization have only minor modulatory roles. However, such factors may be of greater importance under e.g., disease conditions. We also identify areas where single-molecule and muscle data are conflicting: (1) whether force generation is an Eyring or Kramers process with just one major power-stroke or several sub-strokes; (2) whether the myofilaments and the cross-bridges have Hookean or non-linear elasticity; (3) if individual myosin heads slip between actin sites under certain conditions, e.g.,in lengthening; or (4) if the two heads of myosin cooperate.

Place, publisher, year, edition, pages
MDPI, 2018
Keywords
optical tweezers, optical traps, muscle fiber, myofibril, myosin, actin, cross-bridge, mechanochemical model
National Category
Biophysics Biochemistry and Molecular Biology
Research subject
Chemistry, Biochemistry
Identifiers
urn:nbn:se:lnu:diva-77732 (URN)10.3390/ijms19071863 (DOI)000442807400042 ()29941816 (PubMedID)2-s2.0-85049149996 (Scopus ID)
Available from: 2018-09-13 Created: 2018-09-13 Last updated: 2019-08-29Bibliographically approved
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