Heavy riboflavin synthase from Bacillus subtilis

Ladenstein, Rudolf; Meyer, Birgit; Huber, Robert; Labischinski, Harald; Bartels, Klaus; Bartunik, H.D.; Bachmann, L.; Ludwig, Heide C.; Bacher, Adelbert

doi:10.1016/0022-2836(86)90408-0

Cited by 50 publications

(10 citation statements)

References 15 publications

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“…The arm segments of the Only the upper pair of a-helices is shown. the N-terminal segment projects away, but is attached to the /I-sheet of a neighbouring subunit in the pentamer (b); ( c ) is the drawing of the observed c" carbon positions in the pentamer (Ladenstein et al, 1986;.…”

Section: Flexibility In Subunit Assemblymentioning

confidence: 99%

Flexibility and rigidity, requirements for the function of proteins and protein pigment complexes

Huber

1987

Biochemical Society Transactions

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Proteins may be rigid or flexible to various degrees as required for optimum function. Flexibility at the level of amino acid side-chains occurs universally and is important for binding and catalysis. Flexibility of large parts of a protein which rearrange or move are particularly interesting and will be discussed here. We differentiate between certain categories of large-scale flexibility although the boundaries between them are diffuse: flexibility of peptide segments, domain motions and order-disorder transitions of spatially contigous regions. The domains may be flexibly linked to allow rather unrestricted motion or the motion may be constrained to certain modes. The polypeptide segments linking the domains show characteristic structural features. The various categories of flexibility will be illustrated with the following examples. (a) Small protein proteinase inhibitors which are rather rigid molecules which provide binding surfaces complementary to their cognate proteases, but also show limited segmental flexibility and adaptation. (b) Large plasma inhibitors which exhibit large conformational changes upon interaction with proteases probably for regulatory purposes. (c) Pancreatic serine proteases which employ a disorder-order transition of their activation domain as a means to regulate enzymic activity. (d) Immunoglobulins in which rather unrestricted and also hinged domain motions occur in different parts of the molecule probably to allow binding to antigens in different arrangements. (e) Citrate synthase which adopts open and closed forms by a hinged domain motion to bind substrates and release products and to perform the catalytic condensation reaction, respectively. (f) The bifunctional multienzyme complex riboflavin synthase in which two enzymes (alpha and beta) catalyse two consecutive enzymic reactions. The beta-subunits form a shell, in which the alpha-subunits are enclosed. Diffusional motion of the catalytic intermediates is therefore restricted. In addition, segmental rearrangement occurs in the assembly of the beta-subunit. In contrast, rigidity is the dominant impression provided by the structures of the light harvesting complexes and the reaction centres involved the photosynthetic light reactions. These are large protein complexes in which the proteins serve as matrices to hold the pigments in the appropriate conformation and relative arrangement. Since motion would contribute to deactivation of the photo-excited states of the pigments and diminish the efficiency of light energy and electron transfer, a functional role for rigidity is easy to rationalize for these proteins.

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Section: Flexibility In Subunit Assemblymentioning

confidence: 99%

Flexibility and rigidity, requirements for the function of proteins and protein pigment complexes

Huber

1987

Biochemical Society Transactions

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“…T h e b-subunits (lumazine synthase) form a capsid with icosahedral 532 symmetry [10,11]. The a-subunits (riboflavin synthase) form a trimer that is enclosed in the central core of the icosahedral ,&subunit capsid.…”

Section: A9mentioning

confidence: 99%

Biosynthesis of Riboflavin: Structure and mechanism of lumazine synthase

Bacher

Fischer

Kis

et al. 1996

Biochemical Society Transactions

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“…5b) and with one of both particle orientations allowed by the crystal packing model deduced from space group symmetry and electron microscopy. With the help of these data it was clear that the structure of the native complex can be described as an icosahedral capsid of 60 β subunits with the triangulation number T = 1 (22). The spatial orientation of the α subunits located in the central core, however, was incompletely understood at this time.…”

Section: Dealing With Icosahedral Particlesmentioning

confidence: 99%

“…The lattice constants (156 Å) found from the micrographs were in excellent agreement with the values derived from X-ray diffraction data (156.4 Å). From the electron micrographs a packing model was derived which together with the space group symmetry of the crystals (P6 3 22) allowed an unambiguous determination of the translation component of the particles in the crystal (22). Silver and gold decoration patterns mapped by electron microscopy in conjunction with image processing were used to determine approximate values of the orientation of the icosahedral symmetry axes with respect to the crystal cell axes (Fig.…”

Section: Dealing With Icosahedral Particlesmentioning

confidence: 99%