Abstract:
:Cell cultures of Catharanthus roseus were supplied with [2-13C, 3-2H]-deoxyxylulose or [2-13C,4-2H]1-deoxyxylulose. Lutein and chlorophylls were isolated from the cell mass, and hydrolysis of the chlorophyll mixtures afforded phytol. Isotope labeling patterns of phytol and lutein were determined by 2H NMR and 1H,2H-decoupled 13C NMR. From the data it must be concluded that the deuterium atom in position 3 of deoxyxylulose was incorporated into both isopentenyl pyrophosphate (IPP) and dimethylallyl pyrophosphate with a rate of 75% (with respect to the internal 13C label). The detected stereochemical signature implies that the label is located preferentially in the (E)-hydrogen atom of IPP. This preferential labeling, in turn, rules out dimethylallyl pyrophosphate as the compulsory precursor of IPP. In the experiment with [2-13C, 4-2H]1-deoxyxylulose, the 13C label was efficiently transferred to the terpenoids whereas the 2H label was completely washed out, most probably after IPP formation as a consequence of the isomerization and elongation process. In addition, the data cast light on the stereochemical course of the dehydrogenation and cyclization steps involved in the biosynthesis of lutein.
journal_name
Proc Natl Acad Sci U S Aauthors
Arigoni D,Eisenreich W,Latzel C,Sagner S,Radykewicz T,Zenk MH,Bacher Adoi
10.1073/pnas.96.4.1309subject
Has Abstractpub_date
1999-02-16 00:00:00pages
1309-14issue
4eissn
0027-8424issn
1091-6490journal_volume
96pub_type
杂志文章abstract::HetR is an essential regulator of heterocyst development in cyanobacteria. Many mutations in HetR render Anabaena incapable of nitrogen fixation. The protein binds to a DNA palindrome upstream of hetP and other genes. We have determined the crystal structures of HetR complexed with palindromic DNA targets, 21, 23, and...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1305971110
更新日期:2013-05-07 00:00:00
abstract::Blood oxygen level-dependent functional MRI (fMRI) constitutes a powerful neuroimaging technology to map brain-wide functions in response to specific sensory or cognitive tasks. However, fMRI mapping of the vestibular system, which is pivotal for our sense of balance, poses significant challenges. Physical constraints...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1812453116
更新日期:2019-05-14 00:00:00
abstract::The heat-stable enterotoxin B (STB) of Escherichia coli is a 48-amino acid extracellular peptide that induces rapid fluid accumulation in animal intestinal models. Unlike other E. coli enterotoxins that elicit cAMP or cGMP responses in the gut [heat-labile toxin (LT) and heat-stable toxin A (STA), respectively], STB i...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.90.8.3202
更新日期:1993-04-15 00:00:00
abstract::Small proteins can fold remarkably rapidly, even in μs. What limits their rate of folding? The Engrailed homeodomain is a particularly well-characterized example, which folds ultrafast via an intermediate, I, of solved structure. It is a puzzle that the helix2-turn-helix3 motif of the 3-helix bundle forms in approxima...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1011666107
更新日期:2010-12-21 00:00:00
abstract::Intact squid axons were injected with aequorin and bathed in 3 mM Ca seawater (a concentration close to that of squid blood). Sodium and potassium currents were pharmacologically blocked and repetitive voltage-clamp pulses of a duration of 1.5 ms were applied (to simulate the duration of an action potential) at amplit...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.82.6.1847
更新日期:1985-03-01 00:00:00
abstract::The core enzyme of Escherichia coli RNA polymerase acquires essential promoter recognition and transcription initiation activities by binding one of several sigma subunits. To characterize the proximity between sigma70, the major sigma for transcription of the growth-related genes, and the core enzyme subunits (alpha2...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.95.11.6021
更新日期:1998-05-26 00:00:00
abstract::We have examined the extent of tyrosine phosphorylation of talin, a component of the cytoskeleton localized in the focal adhesions and, therefore, a potential substrate of p60v-src, the transforming protein of Rous sarcoma virus. p60v-src is a tyrosine kinase that induces high levels of phosphotyrosine and the disorga...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.83.15.5507
更新日期:1986-08-01 00:00:00
abstract::The inward Na+ current underlying the action potential in nerve is terminated by inactivation. The preceding report shows that deletions within the intracellular linker between domains III and IV remove inactivation, but mutation of conserved basic and paired acidic amino acids has little effect. Here we show that sub...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.89.22.10910
更新日期:1992-11-15 00:00:00
abstract::Previous studies have shown that DNA methyltransferase (Dnmt) 1 is required for maintenance of bulk DNA methylation and is essential for mouse development. However, somatic disruption of DNMT1 in the human cancer cell line HCT116 was not lethal and caused only minor decreases in methylation. Here, we report the identi...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0604602103
更新日期:2006-09-19 00:00:00
abstract::Steroidogenic factor-1 (SF-1) and liver receptor homologue-1 (LRH-1) belong to the fushi tarazu factor 1 subfamily of nuclear receptors. SF-1 is an essential factor for sex determination during development and regulates adrenal and gonadal steroidogenesis in the adult, whereas LRH-1 is a critical factor for developmen...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0409482102
更新日期:2005-05-24 00:00:00
abstract::[PSI+] is a genetic element in yeast for which a heritable change in phenotype appears to be caused by a heritable change in the conformational state of the Sup35 protein. The inheritance of [PSI+] and the physical state of Sup35 in vivo depend on the protein chaperone Hsp104 (heat shock protein 104). Although these o...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.94.25.13932
更新日期:1997-12-09 00:00:00
abstract::The human brain relies upon the dynamic formation and dissolution of a hierarchy of functional networks to support ongoing cognition. However, how functional connectivities underlying such networks are supported by cortical microstructure remains poorly understood. Recent animal work has demonstrated that electrical a...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1608587113
更新日期:2016-11-22 00:00:00
abstract::The conservation of developmental functions exerted by Antp-class homeoproteins in protostomes and deuterostomes suggested that homologs with related functions are present in diploblastic animals. Our phylogenetic analyses showed that Antp-class homeodomains belong either to non-Hox or to Hox/paraHox families. Among t...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.97.9.4493
更新日期:2000-04-25 00:00:00
abstract::The ability to identify sequences in a randomly encoded polypeptide library that are capable of acquiring unique and stably folded structures would be valuable in the examination of protein-folding issues. The quality control system of the yeast secretory pathway prevents the release of incompletely folded polypeptide...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.102172099
更新日期:2002-05-14 00:00:00
abstract::We identified previously in vitro LRP4 (low-density lipoprotein receptor-related protein 4) as a facilitator of the WNT (Wingless-type) antagonist sclerostin and found mutations disrupting this function to be associated with high bone mass in humans similar to patients lacking sclerostin. To further delineate the role...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1413828111
更新日期:2014-12-02 00:00:00
abstract::CD95 type I and II cells differ in their dependence on mitochondria to execute apoptosis, because antiapoptotic members of the Bcl-2 family render only type II cells resistant to death receptor-induced apoptosis. They can also be distinguished by a more efficient formation of the death-inducing signaling complex in ty...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.2034995100
更新日期:2003-09-30 00:00:00
abstract::Cigarette smoking causes emphysema, a fatal disease involving extensive structural and functional damage of the lung. Using a guinea pig model and human lung cells, we show that oxidant(s) present in tobacco smoke not only cause direct oxidative damage of lung proteins, contributing to the major share of lung injury, ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1600056113
更新日期:2016-07-19 00:00:00
abstract::Highly purified globin mRNA from ducks was copied with RNA-directed DNA polymerase from avian myeloblastosis virus into anti-messenger DNA. With excess RNA, more than 90% of this DNA annealed back to its template with a C(o)t/2 value of 7.5 x 10(-4) mol.sec. liter(-1); the melting temperature of the hybrid was 86 degr...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.70.4.1122
更新日期:1973-04-01 00:00:00
abstract::HBc, the capsid-forming "core protein" of human hepatitis B virus (HBV), is a multidomain, α-helical homodimer that aggressively forms human HBV capsids. Structural plasticity has been proposed to be important to the myriad functions HBc mediates during viral replication. Here, we report detailed thermodynamic analyse...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1308846110
更新日期:2013-07-23 00:00:00
abstract::Fluctuations in resting-state functional connectivity occur but their behavioral significance remains unclear, largely because correlating behavioral state with dynamic functional connectivity states (DCS) engages probes that disrupt the very behavioral state we seek to observe. Observing spontaneous eyelid closures f...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1523980113
更新日期:2016-08-23 00:00:00
abstract::Levinthal's paradox is that finding the native folded state of a protein by a random search among all possible configurations can take an enormously long time. Yet proteins can fold in seconds or less. Mathematical analysis of a simple model shows that a small and physically reasonable energy bias against locally unfa...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.89.1.20
更新日期:1992-01-01 00:00:00
abstract::Dominant mutations in the maize homeobox gene knotted1 (kn1) act nonautonomously during maize leaf development, indicating that Kn1 is involved in the generation or transmission of a developmental signal that passes from the inner layers of the leaf to epidermal cells. We previously found that this nonautonomous activ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.052484099
更新日期:2002-03-19 00:00:00
abstract::Chromosome 14 was transferred into tumorigenic nasopharyngeal carcinoma and esophageal carcinoma cell lines by a microcell-mediated chromosome transfer approach. Functional complementation of defects present in the cancer cells suppressed tumor formation. A candidate tumor-suppressor gene, cysteine-rich intestinal pro...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1101747108
更新日期:2011-05-17 00:00:00
abstract::In 1999, the population of Vancouver Island, Canada, began to experience an outbreak of a fatal fungal disease caused by a highly virulent lineage of Cryptococcus gattii. This organism has recently spread to the Canadian mainland and Pacific Northwest, but the molecular cause of the outbreak remains unknown. Here we s...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0902963106
更新日期:2009-08-04 00:00:00
abstract::The cytochrome bc1 and related complexes are essential energy-conserving components of mitochondrial and bacterial electron transport chains. They orchestrate a complex sequence of electron and proton transfer reactions resulting in the oxidation of quinol, the reduction of a mobile electron carrier, and the transloca...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0702621104
更新日期:2007-05-08 00:00:00
abstract::The issue of protein dynamics and its implications in the biological function of proteins are arousing greater and greater interest in different fields of molecular biology. In cryo-electron tomography experiments one may take several snapshots of a given biological macromolecule. In principle, a large enough collecti...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0400119101
更新日期:2004-04-27 00:00:00
abstract::Of two closely related species of geese, one, the greylag goose, lives in the Indian plains all year round, while the other, the bar-headed goose, lives at the Tibetan lakes and migrates across the Himalayas to winter in India. Another species, the Andean goose, lives in the High Andes all year round. Possession of a ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.88.15.6519
更新日期:1991-08-01 00:00:00
abstract::We have examined the process by which small groups of pigmented germinal cells transplanted orthotopically from stage 30-38 donor embryos into stage 28-38 albino hosts contribute new postmitotic cells to the pigmented retinal epithelium of the growing larval eye in Xenopus. In the great majority of chimeric eyes, the ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.84.10.3302
更新日期:1987-05-01 00:00:00
abstract::Recent demonstrations of correlated low-frequency MRI signal variations between subregions of the spinal cord at rest in humans, similar to those found in the brain, suggest that such resting-state functional connectivity constitutes a common feature of the intrinsic organization of the entire central nervous system. ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1424106112
更新日期:2015-05-12 00:00:00
abstract::Hormones and nutrients often induce genetic programs via signaling pathways that interface with gene-specific activators. Activation of the cAMP pathway, for example, stimulates cellular gene expression by means of the PKA-mediated phosphorylation of cAMP-response element binding protein (CREB) at Ser-133. Here, we us...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0501076102
更新日期:2005-03-22 00:00:00