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SUMMARY:Keynote 3\, Prof. Richard Neutze: Time-resolved diffraction experi
 ments at X-ray free electron lasers reveal ultrafast structural changes in
  photosynthesis
DTSTART;VALUE=DATE-TIME:20191009T144500Z
DTEND;VALUE=DATE-TIME:20191009T152500Z
DTSTAMP;VALUE=DATE-TIME:20260525T090955Z
UID:indico-contribution-135-758@lindico453.srv.lu.se
DESCRIPTION:Speakers: Richard Neutze (Gothenburg University)\nX-ray free e
 lectron lasers (XFEL) have sparked the development of time-resolved serial
  femtosecond crystallography (TR-SFX)\, which is a completely new experime
 ntal approach to understanding protein structural dynamics. We have used T
 R-SFX at the LCLS (an XFEL in California) to probe light-driven structural
  changes from picoseconds to microseconds in a bacterial photosynthetic re
 action centre. These integral membrane proteins harvest sunlight in order 
 to transfer electrons from a special pair of bacteriochlorophylls to quino
 ne molecules that are located on the opposite side of an energy transducin
 g biological membrane. Coupled redox reactions balance the charges and thi
 s leads to a net effect of two pumped protons per photon absorbed. TR-SFX 
 studies at the LCLS revealed structural changes on the picosecond time-sca
 le near the special pair (which is photo-oxidized by light) and the tightl
 y bound menaquinone (which accepts an electron from the special pair). The
 se structural results provide novel chemical insight into how protein stru
 ctural dynamics are able to help to stabilize the charge separated state. 
 With the extension of serial crystallography to synchrotron radiation sour
 ces\, I argue that time-resolved diffraction studies will become more comm
 on in the future as new approaches allow new biological systems to be prob
 ed.\n\nhttps://lindico453.srv.lu.se/event/125/contributions/758/
LOCATION:Kulturen Auditorium
URL:https://lindico453.srv.lu.se/event/125/contributions/758/
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SUMMARY:Short Talk 3\, Viktoria Bågenholm - Two GH26 β-mannanases from B
 acteroides ovatus: structure and role in galactomannan degradation
DTSTART;VALUE=DATE-TIME:20191009T142500Z
DTEND;VALUE=DATE-TIME:20191009T144500Z
DTSTAMP;VALUE=DATE-TIME:20260525T090955Z
UID:indico-contribution-135-757@lindico453.srv.lu.se
DESCRIPTION:Speakers: Viktoria Bågenholm (Lund University)\nGalactomannan
 s are hemicelluloses composed of a β-1\,4-linked mannose backbone with α
 -1\,6-galactose substitutions.\nThey are part of our diet as seed storage 
 polysacchardies and food thickeners and are utilised\nby several human gut
  bacteria (1). One such bacteria\, Bacteroides ovatus\, contains a gene cl
 uster encoding\ntwo glycoside hydrolase family 26 β-mannanases\, BoMan26A
  and BoMan26B (2). BoMan26B generates a\nrange of product lengths upon man
 nan hydrolysis\, prefers longer substrates and is less restricted by galac
 tose\nside-groups than BoMan26A\, which mainly generates mannobiose (3\,4)
 . The results suggest that BoMan26B\nperforms the initial attack on galact
 omannan\, generating oligosaccharides that are further hydrolysed by Bo-\n
 Man26A. Crystal structures of these two enzymes reveal the structural basi
 s for their biochemical differences.\nBoMan26B\, with galactosyl-mannotetr
 aose bound in subsites –5 to –2\, has an open and long active site cle
 ft\nwith W112 in subsite –5 concluded to be involved in mannosyl interac
 tion (4). Moreover\, K149 in the –4 subsite\ninteracted with the galacto
 syl side-group of the ligand\, which may indicate a preference in for subs
 tituted\nmanno-oligosaccharides (4). BoMan26A instead revealed a narrow ac
 tive site cleft that is restricted in one end\nby a loop\, explaining its 
 preference for generating shorter products (6).\n\n1. Kulcinskaja\, E.\, A
 . Rosengren\, R. Ibrahim\, K. Kolenova and H. Stalbrand Appl Environ Micro
 biol (2013). 79:\n133-140\n2. Martens\, E. C.\, E. C. Lowe\, H. Chiang\, N
 . A. Pudlo\, M. Wu\, N. P. McNulty\, D. W. Abbott\, B. Henrissat\, H. J.\n
 Gilbert\, D. N. Bolam and J. I. Gordon PLoS Biol (2011). 9: e1001221\n3. B
 ågenholm\, V.\, S. K. Reddy\, H. Bouraoui\, J. Morrill\, E. Kulcinskaja\,
  C. M.\, Bahr\, O. Aurelius\, T. Rogers\,\nY.Xiao\, D. T. Logan\, E. C. Ma
 rtens\, N. M. Koropatkin and H. Stålbrand J Biol Chem (2017). 292: 229-24
 3\n4. Bågenholm\, V.\, M. Wiemann\, S. K. Reddy\, A. Bhattacharya\, A. Ro
 sengren\, D. T. Logan and H. Stålbrand J\nBiol Chem (2019). 294: 9100-911
 7\n\nhttps://lindico453.srv.lu.se/event/125/contributions/757/
LOCATION:Kulturen Auditorium
URL:https://lindico453.srv.lu.se/event/125/contributions/757/
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