RESUMO
Multisite phosphorylation of proteins is a common mechanism for signal integration and amplification in eukaryotic signaling networks. Proteins are commonly phosphorylated at multiple sites in an ordered manner, whereby phosphorylation by one kinase primes the substrate by generating a recognition motif for a second kinase. Here we show that substrate priming promotes phosphorylation by Saccharomyces cerevisiae Kin1 and Kin2, kinases that regulate cell polarity, exocytosis, and the endoplasmic reticulum (ER) stress response. Kin1/Kin2 phosphorylated substrates within the context of a sequence motif distinct from those of their most closely related kinases. In particular, the rate of phosphorylation of a peptide substrate by Kin1/Kin2 increased >30-fold with incorporation of a phosphoserine residue two residues downstream of the phosphorylation site. Recognition of phosphorylated substrates by Kin1/Kin2 was mediated by a patch of basic residues located in the region of the kinase αC helix. We identified a set of candidate Kin1/Kin2 substrates reported to be dually phosphorylated at sites conforming to the Kin1/Kin2 consensus sequence. One of these proteins, the t-SNARE protein Sec9, was confirmed to be a Kin1/Kin2 substrate both in vitro and in vivo Sec9 phosphorylation by Kin1 in vitro was enhanced by prior phosphorylation at the +2 position. Recognition of primed substrates was not required for the ability of Kin2 to suppress the growth defect of secretory pathway mutants but was necessary for optimal growth under conditions of ER stress. These results suggest that at least some endogenous protein substrates of Kin1/Kin2 are phosphorylated in a priming-dependent manner.
Assuntos
Proteínas de Membrana/metabolismo , Proteínas Serina-Treonina Quinases/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/enzimologia , Motivos de Aminoácidos , Proteínas de Membrana/química , Proteínas de Membrana/genética , Peptídeos/química , Peptídeos/metabolismo , Fosforilação , Proteínas Serina-Treonina Quinases/química , Proteínas Serina-Treonina Quinases/genética , Proteínas Qc-SNARE/genética , Proteínas Qc-SNARE/metabolismo , Saccharomyces cerevisiae/química , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/química , Proteínas de Saccharomyces cerevisiae/genética , Especificidade por SubstratoRESUMO
Helobdella bowermani n. sp. is described from specimens collected in fine sediment of open water benthos of Upper Klamath Lake, Klamath County, Oregon. The new species has pale yellow/buff coloration with scattered chromatophore blotches throughout the dorsal surface, lateral extensions or papillae only on the a2 annulus, dorsal medial row of papillae with small papilla on al and larger papillae on a2 and a3, and a small oval scute (rarely triangular). Helobdella bowermani n. sp. is morphologically similar to Helobdella atli and Helobdella simplex. Molecular comparison of CO-I sequence data from H. bowermani n. sp. revealed differences of 10.6/--10.8% with Helobdella californica, differences of 12.2%-13.7% with H. atli, and differences of 12.7%-13.2% with H. simplex.
Assuntos
Sanguessugas/anatomia & histologia , Sanguessugas/classificação , Distribuição Animal , Animais , Complexo IV da Cadeia de Transporte de Elétrons/genética , Sanguessugas/genética , Oregon , Filogenia , Especificidade da EspécieRESUMO
Alboglossiphoniapallida (Verrill, 1872) comb. nov. is resurrected and redescribed based on morphological and molecular data from specimens of the type locality (New Haven County, Connecticut, USA) that demonstrate it is distinct from North American Alboglossiphoniaheteroclita, European Alboglossiphoniaheteroclita, and Alboglossiphoniapapillosa. Alboglossiphoniapallida is characterized by having dark chromatophores on the dorsal surface arranged lateral to patrilaterally and medially as a thin line or interrupted thin line along with three pairs of eye spots (with the first pair closest together), six pairs of crop ceca, and a united gonopore. Additional sampling of specimens of the genus Alboglossiphonia is needed to understand its phylogeny especially as many species have not been collected since their description.
RESUMO
During cellular stress in the budding yeast Saccharomyces cerevisiae, an endoplasmic reticulum (ER)-resident dual kinase and RNase Ire1 splices an intron from HAC1 mRNA in the cytosol, thereby releasing its translational block. Hac1 protein then activates an adaptive cellular stress response called the unfolded protein response (UPR) that maintains ER homeostasis. The polarity-inducing protein kinases Kin1 and Kin2 contribute to HAC1 mRNA processing. Here, we showed that an RNA-protein complex that included the endocytic proteins Pal1 and Pal2 mediated HAC1 mRNA splicing downstream of Kin1 and Kin2. We found that Pal1 and Pal2 bound to the 3' untranslated region (3'UTR) of HAC1 mRNA, and a yeast strain lacking both Pal1 and Pal2 was deficient in HAC1 mRNA processing. We also showed that Kin1 and Kin2 directly phosphorylated Pal2, and that a nonphosphorylatable Pal2 mutant could not rescue the UPR defect in a pal1Δ pal2Δ strain. Thus, our work uncovers a Kin1/2-Pal2 signaling pathway that coordinates HAC1 mRNA processing and ER homeostasis.
Assuntos
Splicing de RNA , Proteínas de Saccharomyces cerevisiae , Saccharomyces cerevisiae , Resposta a Proteínas não Dobradas , Fatores de Transcrição de Zíper de Leucina Básica/genética , Glicoproteínas de Membrana/metabolismo , Proteínas de Membrana/metabolismo , Fosforilação , Proteínas Quinases , Proteínas Serina-Treonina Quinases/genética , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Proteínas Repressoras/genética , Proteínas Repressoras/metabolismo , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismoRESUMO
To date, the only species of leech reported from the American Alligator, Alligator mississippiensis is Placobdella multilineata. Seven specimens of a previously undescribed species of Placobdella were collected from the feet and lower jaw of a single female alligator from the Pascagoula River Wildlife Management Area, George County, Mississippi. The new species was named Placobdella siddalli Richardson & Moser, sp. n., in honor of the contributions of Dr. Mark Siddall to our understanding of the biology of leeches. Placobdella siddalli Richardson & Moser is similar to other papillated members of the genus Placobdella, but differs from Placobdella ali Hughes & Siddall, 2007, Placobdella rugosa (Verrill, 1874), Placobdella multilineata Moore, 1953, and Placobdella papillifera (Verrill, 1872) in coloration, papillation, ventral striping, and in the possession of a relatively large caudal sucker. In addition, molecular comparison of 626 nucleotides of CO-I between the new species and other papillated leeches (P. ali, P. multilineata, Placobdella ornata, P. papillifera, P. rugosa) revealed interspecific differences of 14.0-18.0% (88-113 nucleotides).
RESUMO
The hellbender (Cryptobranchus alleganiensis) is among the most intriguing and imperiled amphibians in North America. Since the 1970s and 80s, western populations of the Ozark and eastern subspecies in Missouri have declined by nearly 80%. As a result of population declines, the Ozark hellbender was recently federally protected as an endangered species, and the eastern subspecies was granted protection under CITES. Although habitat degradation is probably the biggest threat to hellbender populations, recent evidence suggests that pathogens including chytrid fungus and "flesh-eating" bacteria may also contribute to declines in Ozark hellbenders. Leeches, which are very common on Ozark hellbenders, have recently been implicated as possible vectors of disease among Ozark hellbenders but have not been described in eastern hellbenders or outside of Missouri and Arkansas. We discovered a population of leeches on eastern hellbenders in southwest Virginia and confirmed that the species of leech is within the genus Placobdella, but is morphologically and genetically distinct from all previously described leech species. We named the new species Placobdella appalachiensis sp. n. Moser and Hopkins, based on the mountainous region in which it was discovered. Our surveys over a three consecutive year period suggested that this leech species may be patchily distributed and/or have a narrow geographic range. We consistently detected leeches at one site (mean prevalence in 80 hellbenders = 27.5%; median intensity = 3.0 leeches per parasitized hellbender [range 1 - >250 leeches]) during three years of surveys, but we never found leeches in any of our other seven study sites in two streams (mean prevalence in 139 hellbenders = 0%). We found a significant positive relationship between hellbender body size and the intensity of parasitism, and we suggest the possibility that the behavioral ecology of adults leading up to reproduction may increase their encounter rates with parasites. We discuss the potential conservation implications of discovery of leeches in this stream, and make recommendations for future mitigation and monitoring efforts.
RESUMO
Placobdella cryptobranchii (Johnson & Klemm, 1977) was originally described from specimens collected from Ozark Hellbenders (Cryptobranchus alleganiensis bishopi) from the North Fork of the White River in Missouri, U.S.A. Leeches collected during August 2009 to August 2011 from five localities in Missouri (including the type locality) facilitated a redescription and molecular characterization of Placobdella cryptobranchii. Placobdella cryptobranchii has a rusty, reddish-brown dorsum with 2 lateral rows of unpigmented papillae, two unpigmented nuchal bands, unpigmented patches, and pair of four pre-anal papillae. Molecular comparison of CO-I sequence data from Placobdella cryptobranchii revealed a 93-94% similarity to Placobdella ornata and 10-17% difference among other species of Placobdella.