scholarly journals Genome-wide analysis of Homo sapiens, Arabidopsis thaliana, and Saccharomyces cerevisiae reveals novel attributes of tail-anchored membrane proteins

BMC Genomics ◽  
2019 ◽  
Vol 20 (1) ◽  
Author(s):  
Glauber Costa Brito ◽  
Wiebke Schormann ◽  
Satinder K. Gidda ◽  
Robert T. Mullen ◽  
David W. Andrews

Abstract Background Tail-anchored membrane proteins (TAMPs) differ from other integral membrane proteins, because they contain a single transmembrane domain at the extreme carboxyl-terminus and are therefore obliged to target to membranes post-translationally. Although 3–5% of all transmembrane proteins are predicted to be TAMPs only a small number are well characterized. Results To identify novel putative TAMPs across different species, we used TAMPfinder software to identify 859, 657 and 119 putative TAMPs in human (Homo sapiens), plant (Arabidopsis thaliana), and yeast (Saccharomyces cerevisiae), respectively. Bioinformatics analyses of these putative TAMP sequences suggest that the list is highly enriched for authentic TAMPs. To experimentally validate the software predictions several human and plant proteins identified by TAMPfinder that were previously uncharacterized were expressed in cells and visualized at subcellular membranes by fluorescence microscopy and further analyzed by carbonate extraction or by bimolecular fluorescence complementation. With the exception of the pro-apoptotic protein harakiri, which is, peripherally bound to the membrane this subset of novel proteins behave like genuine TAMPs. Comprehensive bioinformatics analysis of the generated TAMP datasets revealed previously unappreciated common and species-specific features such as the unusual size distribution of and the propensity of TAMP proteins to be part of larger complexes. Additionally, novel features of the amino acid sequences that anchor TAMPs to membranes were also revealed. Conclusions The findings in this study more than double the number of predicted annotated TAMPs and provide new insights into the common and species-specific features of TAMPs. Furthermore, the list of TAMPs and annotations provide a resource for further investigation.

2019 ◽  
Vol 94 (2) ◽  
Author(s):  
Weitong Yao ◽  
Takeshi Yoshida ◽  
Saki Hashimoto ◽  
Hiroaki Takeuchi ◽  
Klaus Strebel ◽  
...  

ABSTRACT BST-2/CD317/tetherin is a host transmembrane protein that potently inhibits human immunodeficiency virus type 1 (HIV-1) virion release by tethering the nascent virions to the plasma membrane. Viral protein U (Vpu) is an accessory protein encoded by HIV-1 as well as by some simian immunodeficiency viruses (SIVs) infecting wild chimpanzees, gorillas, or monkeys (SIVcpz, SIVgor, or SIVgsn/SIVmon/SIVmus, respectively). HIV-1 Vpu directly binds to and downregulates human BST-2. The antagonism is highly species specific because the amino acid sequences of BST-2 are different among animal species. Here, we show that Vpu proteins from several SIVcpz, SIVgsn, SIVmon, or SIVmus isolates fail to antagonize human BST-2. Only Vpu from an SIVgsn isolate (SIVgsn-99CM71 [SIVgsn71]) was able to antagonize human BST-2 as well as BST-2 of its natural host, greater spot-nosed monkey (GSN). This SIVgsn Vpu interacted with human BST-2, downregulated cell surface human BST-2 expression, and facilitated HIV-1 virion release in the presence of human BST-2. While the unique 14AxxxxxxxW22 motif in the transmembrane domain of HIV-1NL4-3Vpu was reported to be important for antagonizing human BST-2, we show here that two AxxxxxxxW motifs (A22W30 and A25W33) exist in SIVgsn71 Vpu. Only the A22W30 motif was needed for SIVgsn71 Vpu to antagonize GSN BST-2, suggesting that the mechanism of this antagonism resembles that of HIV-1NL4-3 Vpu against human BST-2. Interestingly, SIVgsn71 Vpu requires two AxxxxxxxW (A22W30 and A25W33) motifs to antagonize human BST-2, suggesting an as-yet-undefined way that SIVgsn71 Vpu works against human BST-2. These results imply an evolutionary impact of primate BST-2 on lentiviral Vpu. IMPORTANCE Genetic alterations conferring a selective advantage in protecting from life-threating pathogens are maintained during evolution. In fact, the amino acid sequences of BST-2 differ among primate animals and their susceptibility to viral proteins is species specific, suggesting that such genetic diversity has arisen through the evolutionarily controlled balance between the host and pathogens. The M (main) group of HIV-1 is thought to be derived from SIVcpz, which utilizes Nef, but not Vpu, to antagonize chimpanzee BST-2. SIVcpz Nef is, however, unable to antagonize human BST-2, and Vpu was consequently chosen again as an antagonist against human BST-2 in the context of HIV-1. Studies on how Vpu lost and acquired this ability, together with the distinct mechanisms by which SIVgsn71 Vpu binds to and downregulates human or GSN BST-2, may help to explain the evolution of this lentiviral protein as a result of host-pathogen interactions.


1987 ◽  
Vol 262 (2) ◽  
pp. 546-548
Author(s):  
R Betz ◽  
J W Crabb ◽  
H E Meyer ◽  
R Wittig ◽  
W Duntze

Genetics ◽  
1998 ◽  
Vol 149 (3) ◽  
pp. 1277-1292 ◽  
Author(s):  
Rajesh R Naik ◽  
Elizabeth W Jones

Abstract The vacuolar hydrolase protease B in Saccharomyces cerevisiae is synthesized as an inactive precursor (Prb1p). The precursor undergoes post-translational modifications while transiting the secretory pathway. In addition to N- and O -linked glycosylations, four proteolytic cleavages occur during the maturation of Prb1p. Removal of the signal peptide by signal peptidase and the autocatalytic cleavage of the large aminoterminal propeptide occur in the endoplasmic reticulum (ER). Two carboxy-terminal cleavages of the post regions occur in the vacuole: the first cleavage is catalyzed by protease A and the second results from autocatalysis. We have isolated a mutant, pbn1-1, that exhibits a defect in the ER processing of Prb1p. The autocatalytic cleavage of the propeptide from Prb1p does not occur and Prb1p is rapidly degraded in the cytosol. PBN1 was cloned and is identical to YCL052c on chromosome III. PBN1 is an essential gene that encodes a novel protein. Pbn1p is predicted to contain a sub-C-terminal transmembrane domain but no signal sequence. A functional HA epitope-tagged Pbn1p fusion localizes to the ER. Pbn1p is N-glycosylated in its amino-terminal domain, indicating a lumenal orientation despite the lack of a signal sequence. Based on these results, we propose that one of the functions of Pbn1p is to aid in the autocatalytic processing of Prb1p.


Genetics ◽  
2001 ◽  
Vol 158 (4) ◽  
pp. 1697-1710 ◽  
Author(s):  
Shozo Yokoyama ◽  
F Bernhard Radlwimmer

Abstract To better understand the evolution of red-green color vision in vertebrates, we inferred the amino acid sequences of the ancestral pigments of 11 selected visual pigments: the LWS pigments of cave fish (Astyanax fasciatus), frog (Xenopus laevis), chicken (Gallus gallus), chameleon (Anolis carolinensis), goat (Capra hircus), and human (Homo sapiens); and the MWS pigments of cave fish, gecko (Gekko gekko), mouse (Mus musculus), squirrel (Sciurus carolinensis), and human. We constructed these ancestral pigments by introducing the necessary mutations into contemporary pigments and evaluated their absorption spectra using an in vitro assay. The results show that the common ancestor of vertebrates and most other ancestors had LWS pigments. Multiple regression analyses of ancestral and contemporary MWS and LWS pigments show that single mutations S180A, H197Y, Y277F, T285A, A308S, and double mutations S180A/H197Y shift the λmax of the pigments by −7, −28, −8, −15, −27, and 11 nm, respectively. It is most likely that this “five-sites” rule is the molecular basis of spectral tuning in the MWS and LWS pigments during vertebrate evolution.


2011 ◽  
Vol 89 (2) ◽  
pp. 224-235 ◽  
Author(s):  
Andrew K. Stewart ◽  
Fouad T. Chebib ◽  
Syed W. Akbar ◽  
Maria J. Salas ◽  
Rajan A. Sonik ◽  
...  

The AE1 mutation G701D, associated with recessive distal renal tubular acidosis (dRTA), produces only minimal erythroid phenotype, reflecting erythroid-specific expression of stimulatory AE1 subunit glycophorin A (GPA). GPA transgene expression could theoretically treat recessive dRTA in patients and in mice expressing cognate Ae1 mutation G719D. However, human (h) GPA and mouse (m) Gpa amino acid sequences are widely divergent, and mGpa function in vitro has not been investigated. We therefore studied in Xenopus oocytes the effects of coexpressed mGpa and hGPA on anion transport by erythroid (e) and kidney (k) isoforms of wild-type mAe1 (meAe1, mkAe1) and of mAe1 mutant G719D. Coexpression of hGPA or mGpa enhanced the function of meAe1 and mkAe1 and rescued the nonfunctional meAe1 and mkAe1 G719D mutants through increased surface expression. Progressive N-terminal truncation studies revealed a role for meAe1 amino acids 22–28 in GPA-responsiveness of meAe1 G719D. MouseN-cyto/humanTMD and humanN-cyto/mouseTMD kAE1 chimeras were active and GPA-responsive. In contrast, whereas chimera mkAe1N-cyto/hkAE1 G701DTMD was GPA-responsive, chimera hkAE1N-cyto/mkAe1 G719DTMD was GPA-insensitive. Moreover, whereas the isolated transmembrane domain (TMD) of hAE1 G701D was GPA-responsive, that of mAe1 G719D was GPA-insensitive. Thus, mGpa increases surface expression and activity of meAe1 and mkAe1. However, the G719D mutation renders certain mAe1 mutant constructs GPA-unresponsive and highlights a role for erythroid-specific meAe1 amino acids 22–28 in GPA-responsiveness.


1999 ◽  
Vol 19 (5) ◽  
pp. 3435-3442 ◽  
Author(s):  
Gregor Steglich ◽  
Walter Neupert ◽  
Thomas Langer

ABSTRACT Prohibitins comprise a protein family in eukaryotic cells with potential roles in senescence and tumor suppression. Phb1p and Phb2p, members of the prohibitin family in Saccharomyces cerevisiae, have been implicated in the regulation of the replicative life span of the cells and in the maintenance of mitochondrial morphology. The functional activities of these proteins, however, have not been elucidated. We demonstrate here that prohibitins regulate the turnover of membrane proteins by the m-AAA protease, a conserved ATP-dependent protease in the inner membrane of mitochondria. The m-AAA protease is composed of the homologous subunits Yta10p (Afg3p) and Yta12p (Rca1p). Deletion ofPHB1 or PHB2 impairs growth of Δyta10 or Δyta12 cells but does not affect cell growth in the presence of the m-AAA protease. A prohibitin complex with a native molecular mass of approximately 2 MDa containing Phb1p and Phb2p forms a supercomplex with them-AAA protease. Proteolysis of nonassembled inner membrane proteins by the m-AAA protease is accelerated in mitochondria lacking Phb1p or Phb2p, indicating a negative regulatory effect of prohibitins on m-AAA protease activity. These results functionally link members of two conserved protein families in eukaryotes to the degradation of membrane proteins in mitochondria.


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