Phosphodiesterases (PDEs) hydrolyze the second messengers cAMP and cGMP. It remains unknown how individual PDE families selectively recognize cAMP and cGMP. This work reports structural studies on substrate specificity. The crystal structures of the catalytic domains of the D674A and D564N mutants of PDE10A2 in complex with cAMP and cGMP reveal that two substrates bind to the active site with the same syn configuration but different orientations and interactions. The products AMP and GMP bind PDE10A2 with the anti configuration and interact with both divalent metals, in contrast to no direct contact of the substrates. The structures suggest that the syn configurations of cAMP and cGMP are the genuine substrates for PDE10 and the specificity is achieved through the different interactions and conformations of the substrates. The PDE10A2 structures also show that the conformation of the invariant glutamine is locked by two hydrogen bonds and is unlikely to switch for substrate recognition. Sequence alignment shows a potential pocket, in which variation of amino acids across PDE families defines the size and shape of the pocket and thus determines the substrate specificity.crystal structure ͉ cyclic nucleotides cAMP and cGMP C yclic nucleotide phosphodiesterases (PDEs) are enzymes hydrolyzing the second messengers adenosine and guanosine 3Ј,5Ј-cyclic monophosphates (cAMP and cGMP). The human genome encodes 21 PDE genes that are categorized into 11 families (1, 2). Selective inhibitors against individual PDE families have been developed as therapeutics for treatment of various human diseases (3-8). The best known examples are the PDE5 inhibitors sildenafil (Viagra), vardenafil (Levitra), and tadalafil (Cialis) that have been used for treatment of male erectile dysfunction (5). Sildenafil (Revatio) has also been approved for treatment of pulmonary hypertension (9). PDE10 was independently identified by three groups in 1999 and shows a dual activity on hydrolysis of both cAMP and cGMP (10-12). PDE10 is highly expressed in brain striatum (13-16). Reduction of PDE10A mRNA and protein levels in striatum of transgenic mice implies a role of PDE10A in Huntington's disease (17,18). Knockout mice experiments suggest that PDE10A is involved in regulating striatal output, possibly by reducing the sensitivity of medium spiny neurons to glutamatergic excitation (19). The PDE10 inhibitor papaverine is effective in improving executive function deficits associated with schizophrenia, and therefore inhibition of PDE10 may represent an approach to treatment of psychosis (20,21).PDE families contain a variable N-terminal regulatory domain and a conserved C-terminal catalytic domain. Individual PDE families show different substrate preferences. Crystal structures have been reported for the catalytic domains of seven PDE families in the unliganded form or in complex with inhibitors or products: PDE1B, PDE2A, PDE3B, PDE4B/4D, PDE5A, PDE7A, and PDE9A (22-34). However, it remains a puzzle how the conserved catalytic pocket of the PDE famili...

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Species-specific sex pheromone is biosynthesized and released in most female moths as a chemical cue in mating communication. However, information on genes involved in this pathway is limited. The beet armyworm, Spodoptera exigua, is a cosmopolitan agricultural pest that causes severe economic losses to many crops. In China, the female sex pheromones in sex pheromone glands (PGs) of S. exigua have been measured which comprises (Z,E)-9,12-tetradecadienyl acetate, (Z)-9-tetradecen-l-ol, (Z)-9-tetradecenyl acetate, and (Z,E)-9,12-tetradecadien-1-ol in a ratio of 47:18:18:17. Fifty-nine putative genes related to sex pheromone biosynthesis were identified in the present study by sequencing and analyzing the sex pheromone gland (PG) transcriptome of S. exigua. Expression profiles revealed that two desaturase (SexiDes5 and SexiDes11) and three fatty acyl reductase (SexiFAR2, 3, and 9) genes had PG-specific expression, and phylogenetic analysis demonstrated that they clustered with genes known to be involved in pheromone synthesis in other moth species. Our results provide crucial background information that could facilitate the elucidation of sex pheromone biosynthesis pathway of S. exigua as well as other Spodoptera species and help identify potential targets for disrupting sexual communication in S. exigua for developing novel environment-friendly pesticides.

Athetis lepigone has been recorded in many countries in Europe and Asia, but it had never been documented as an agricultural pest until 2005. For the purpose of using the sex pheromone to control this pest, we conducted a study to identify the sex pheromone of A. lepigone by gas chromatography with an electroantennographic detector (GC-EAD) and GC coupled with mass spectrometry (GC/MS) analyses. Three pheromone candidates were detected by GC-EAD analysis in the extracts of the female sex pheromone gland, and two candidates were identified as (Z)-7-dodecenyl acetate (Z7-12:OAc) and (Z)-9-tetradecenyl acetate (Z9-14:OAc) in a ratio of 1:5 by mass spectral analysis of natural pheromone components and dimethyl disulphide adducts. In the field male trapping test, the traps baited with the binary blend captured high number of males, while traps with single component hardly caught males, indicating that the two components are essential for the male attractiveness. In addition, the optimum ratios of Z7-12:OAc and Z9-14:OAc were determined as 3:7-7:3, and the best doses for the binary blend (at ratio of 3:7 between Z7-12:OAc and Z9-14:OAc) were 0.25-0.5 mg/trap, based on the number of male catches. The identification of a highly attractive sex pheromone will help in developing efficient strategies for monitoring and control of A. lepigone. K E Y W O R D S(Z)-7-dodecenyl acetate, (Z)-9-tetradecenyl acetate, Athetis lepigone, sex pheromone

Chlorin e6 (Ce6) is a promising photosensitizer for tumor photodynamic therapy (PDT). However, the efficacy of Ce6 PDT is limited by Ce6’s poor water solubility, rapid blood clearance, and inadequate accumulation in the tumor tissue. This problem is tackled in this work, wherein functionalized superparamagnetic iron oxide nanoparticles (IO-NPs) were used as carriers to deliver Ce6 to melanoma. The IO-NPs were coated with polyglycerol (PG) to afford good aqueous solubility. The chemotherapeutic agent doxorubicin (DOX) was attached to the PG coating via the hydrazone bond to afford affinity to the cell membrane and thereby promote the cell uptake. The hydrophobic nature of DOX also induced the aggregation of IO-NPs to form nanoclusters. Ce6 was then loaded onto the IO nanoclusters through physical adsorption and coordination with surface iron atoms, yielding the final composites IO–PG–DOX–Ce6. In vitro experiments showed that IO–PG–DOX–Ce6 markedly increased Ce6 uptake in mouse melanoma cells, leading to much-enhanced photocytotoxicity characterized by intensified reactive oxygen species production, loss of viability, DNA damage, and stimulation of tumor cell immunogenicity. In vivo experiments corroborated the in vitro findings and demonstrated prolonged blood clearance of IO–PG–DOX–Ce6. Importantly, IO–PG–DOX–Ce6 markedly increased the Ce6 distribution and retention in mouse subcutaneous melanoma grafts and significantly improved the efficacy of Ce6-mediated PDT. No apparent vital organ damage was observed at the same time. In conclusion, the IO–PG–DOX NPs provide a simple and safe delivery platform for efficient tumor enrichment of Ce6, thereby enhancing antimelanoma PDT.