PMID- 32786410
OWN - NLM
STAT- MEDLINE
DCOM- 20210317
LR  - 20211022
IS  - 1520-4995 (Electronic)
IS  - 0006-2960 (Print)
IS  - 0006-2960 (Linking)
VI  - 59
IP  - 35
DP  - 2020 Sep 8
TI  - Mechanism Underlying Anti-Markovnikov Addition in the Reaction of Pentalenene 
      Synthase.
PG  - 3271-3283
LID - 10.1021/acs.biochem.0c00518 [doi]
AB  - Most terpene synthase reactions follow Markovnikov rules for formation of 
      high-energy carbenium ion intermediates. However, there are notable exceptions. 
      For example, pentalenene synthase (PS) undergoes an initial anti-Markovnikov 
      cyclization reaction followed by a 1,2-hydride shift to form an intermediate 
      humulyl cation with positive charge on the secondary carbon C9 atom of the 
      farnesyl diphosphate substrate. The mechanism by which these enzymes stabilize 
      and guide the regioselectivity of secondary carbocations has not heretofore been 
      elucidated. In an effort to better understand these reactions, we grew crystals 
      of apo-PS, soaked them with the nonreactive substrate analogue 
      12,13-difluorofarnesyl diphosphate, and determined the X-ray structure of the 
      resulting complex at 2.2 A resolution. The most striking feature of the active 
      site structure is that C9 is perfectly positioned to make a C-H...pi interaction 
      with the side chain benzene ring of residue F76; this would enhance 
      hyperconjugation to stabilize a developing cation at C10 and thus support the 
      anti-Markovnikov regioselectivity of the cyclization. The benzene ring is also 
      positioned to catalyze the migration of H to C10 and stabilize a C9 carbocation. 
      On the opposite face of C9, further cation stabilization is possible via 
      interactions with the main chain carbonyl of I177 and the neighboring 
      intramolecular C6 horizontal lineC7 bond. Mutagenesis experiments also support a role for 
      residue 76 in these interactions, but most interesting is the F76W mutant, whose 
      crystal structure clearly shows C9 and C10 centered above the fused benzene and 
      pyrrole rings of the indole side chain, respectively, such that a carbocation at 
      either position could be stabilized in this complex, and two anti-Markovnikov 
      products, pentalenene and humulene, are formed. Finally, we show that there is a 
      rough correlation (although not absolute) of an aromatic side chain (F or Y) at 
      position 76 in related terpene synthases from Streptomyces that catalyze similar 
      anti-Markovnikov addition reactions.
FAU - Matos, Jason O
AU  - Matos JO
AD  - Department of Biochemistry, Brandeis University, Waltham, Massachusetts 02454, 
      United States.
FAU - Kumar, Ramasamy P
AU  - Kumar RP
AUID- ORCID: 0000-0002-6555-8289
AD  - Department of Biochemistry, Brandeis University, Waltham, Massachusetts 02454, 
      United States.
FAU - Ma, Alison C
AU  - Ma AC
AD  - Department of Biochemistry, Brandeis University, Waltham, Massachusetts 02454, 
      United States.
FAU - Patterson, MacKenzie
AU  - Patterson M
AD  - Department of Biochemistry, Brandeis University, Waltham, Massachusetts 02454, 
      United States.
FAU - Krauss, Isaac J
AU  - Krauss IJ
AUID- ORCID: 0000-0003-0984-4085
AD  - Department of Chemistry, Brandeis University, Waltham, Massachusetts 02454, 
      United States.
FAU - Oprian, Daniel D
AU  - Oprian DD
AUID- ORCID: 0000-0002-6520-5459
AD  - Department of Biochemistry, Brandeis University, Waltham, Massachusetts 02454, 
      United States.
LA  - eng
GR  - T32 GM007596/GM/NIGMS NIH HHS/United States
GR  - T32 GM135126/GM/NIGMS NIH HHS/United States
PT  - Journal Article
PT  - Research Support, N.I.H., Extramural
PT  - Research Support, U.S. Gov't, Non-P.H.S.
DEP - 20200818
PL  - United States
TA  - Biochemistry
JT  - Biochemistry
JID - 0370623
RN  - 0 (Cyclopentanes)
RN  - 62065-26-3 (pentalenene)
RN  - EC 2.5.- (Alkyl and Aryl Transferases)
RN  - EC 2.5.1.- (terpene synthase)
RN  - EC 5.5.- (Intramolecular Lyases)
RN  - EC 5.5.- (farnesylpyrophosphate cyclase)
SB  - IM
MH  - Alkyl and Aryl Transferases/chemistry/metabolism
MH  - Catalysis
MH  - Catalytic Domain
MH  - Crystallography, X-Ray
MH  - Cyclization
MH  - Cyclopentanes/chemistry/metabolism
MH  - Intramolecular Lyases/*chemistry/*metabolism
MH  - Models, Molecular
MH  - Protein Conformation
MH  - Streptomyces/*enzymology
PMC - PMC7484107
MID - NIHMS1619524
COIS- Competing interests The authors declare no competing financial interest.
EDAT- 2020/08/14 06:00
MHDA- 2021/03/18 06:00
PMCR- 2021/09/08
CRDT- 2020/08/14 06:00
PHST- 2020/08/14 06:00 [pubmed]
PHST- 2021/03/18 06:00 [medline]
PHST- 2020/08/14 06:00 [entrez]
PHST- 2021/09/08 00:00 [pmc-release]
AID - 10.1021/acs.biochem.0c00518 [doi]
PST - ppublish
SO  - Biochemistry. 2020 Sep 8;59(35):3271-3283. doi: 10.1021/acs.biochem.0c00518. Epub 
      2020 Aug 18.