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UID:20260304T081743EST-1290buDTgM@132.216.98.100
DTSTAMP:20260304T131743Z
DESCRIPTION:Abstract:\n\nPhotosynthetic CO2 fixation is a fundamental sourc
 e of food\, fuels and chemicals for human society. In the vast majority of
  photosynthetic organisms\, carbon fixation is operated by the Calvin-Bens
 on-Bassman (CBB) cycle [1]. CBB cycle is a pathway consisting of 13 reacti
 ons catalysed by 11 enzymes that are differentially regulated to coordinat
 e the entire photosynthetic process in a constantly changing light environ
 ment.\n	Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and phosphoribulok
 inase (PRK) are two enzymes of the CBB cycle sharing peculiar features. Bo
 th enzymes use the products of light reactions for catalysis (NADPH for GA
 PDH\, ATP for PRK)\, are regulated by thioredoxins and in the dark or unde
 r low photosynthetic conditions form inactive supramolecular complex with 
 the regulatory scaffold protein CP12\, mainly under the control of thiored
 oxins and pyridine nucleotides. In the light\, complex dissociation allows
  GAPDH and PRK reactivation.\n	In land plants\, the GAPDH/CP12/PRK complex 
 coexists with an autoassembling heterotetrameric AB-GAPDH that is analogou
 sly regulated. Using small-angle X-ray scattering coupled with size-exclus
 ion chromatography (SEC-SAXS) and cryo-electron microscopy (cryo-EM)\, we 
 identified several oligomeric forms of AB-GAPDH [(A2B2)n-GAPDH oligomers w
 ith n=1\, 2\, 4\, and 5] coexisting in a dynamic equilibrium [2]. Due to t
 he sample's high compositional and conformational heterogeneity\, we were 
 able to resolve the structures of AB-GAPDH oligomers at resolution of appr
 oximately 3 Å for the two hexameric conformations of the most abundant oli
 gomer A8B8.\n	The regulation of PRK rely on a pair of cysteines located in 
 the active site\, but not directly involved in catalysis. The crystal stru
 cture of PRK in reduced and oxidized form has elucidated the inhibition me
 chanism of this enzyme [3\,4]. The structural comparison between eukaryoti
 c and cyanobacterial PRKs\, shows that the last lacks a loop of eighteen a
 mino acids (named clamp loop) between the two regulatory cysteines\, which
  has been proposed to participate in TRX binding [3]. Moreover\, in order 
 to investigate the PRK ligand and substrate binding mode\, the crystal str
 uctures of CrPRK in complex with ATP and with ADP/Ru5P or AMP-PCP/Ru5P hav
 e been described.\n	With the recently described 3D structures of PRK\, A4-G
 APDH/CP12/PRK complex and AB-GAPDH oligomers the structural proteome of th
 is ubiquitous regulatory system has been completed. This outcome opens a n
 ew avenue for understanding the regulatory potential of photosynthetic car
 bon fixation by laying the foundation for its knowledge-based manipulation
 .\n	[1] Michelet\, L.\, Zaffagnini\, M.\, Morisse\, S.\, Sparla\, F.\, Pére
 z-Pérez\, M.E.\, Francia\, F.\, Danon\, A.\, Marchand\, C.H.\, Fermani\, S
 .\, Trost\, P.\, & Lemaire\, S.D. (2013) Front. Plant Sci\, 4\, 470.\n	[2] 
 Marotta\, R.\, Del Giudice\, A.\, Gurrieri\, L.\, Fanti\, S.\, Swuec\, P.\
 , Galantini\, L.\, Falini\, G.\, Trost\, P.\, Fermani\, S. & Sparla\, F. (
 2022) Acta Crystallogr. D Struct. Biol\, 78\, 1399.\n	[3] Gurrieri\, L.\, D
 el Giudice\, A.\, Demitri\, N.\, Falini\, G.\, Pavel\, N. V.\, Zaffagnini\
 , M.\, Polentarutti\, M.\, Crozet\, P.\, Marchand\, C. H.\, Henri\, J. \, 
 Trost\, P.\, Lemaire\, S. D.\, Sparla\, F. & Fermani\, S. (2019) Proc. Nat
 l. Acad. Sci USA\, 116\, 8048.\n	[4] Wilson\, R. H.\, Hayer-Hartl\, M. & Br
 acher. A. (2019) Acta Crystallogr. F75\, 278 \n\nBio:\n\nSimona Fermani is
  Associate Professor in Inorganic Chemistry at the Department of Chemistry
  “G. Ciamician” of the University of Bologna. She has completed her PhD in
  Chemistry in 2000 at the University of Bologna and continued her research
  activity as a post-doc. From 2007-2010\, she worked in a multinational co
 mpany (Nexans). Her research activity is primarily addressed in the field 
 of structural biology focusing on the 3D structures of enzymes from model 
 photosynthetic organisms and biomineralization. She is co-author of more t
 han 120 scientific publications in peer-reviewed journals with impact fact
 or.\n\n \n
DTSTART:20260220T150000Z
DTEND:20260220T160000Z
LOCATION:OM321\, 801 Rue Sherbrooke Ouest\, Maass Chemistry Building\, CA\,
  QC\, Montreal\, H3A 0B8\, 801 rue Sherbrooke Ouest
SUMMARY:91˿����Ƶ Seminar - Simona Fermani: Structural insight into the comple
 x regulation of the Calvin–Benson cycle
URL:/chemistry/channels/event/mcgill-seminar-simona-fe
 rmani-structural-insight-complex-regulation-calvin-benson-cycle-371350
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