Search results for "c space"
showing 10 items of 552 documents
Common fixed points in cone metric spaces for $MK$-pairs and $L$-pairs
2011
In this paper we introduce some contractive conditions of Meir-Keeler type for a pair of mappings, called $MK$-$pair$ and $L\textrm{-}pair$, in the framework of cone metric spaces and we prove theorems which assure existence and uniqueness of common fixed points for $MK$-$pairs$ and $L \textrm{-}pairs$. As an application we obtain a result of common fixed point of a $p$-$MK$-pair, a mapping and a multifunction, in complete cone metric spaces. These results extend and generalize well-known comparable results in the literature.
Common fixed points of g-quasicontractions and related mappings in 0-complete partial metric spaces
2012
Abstract Common fixed point results are obtained in 0-complete partial metric spaces under various contractive conditions, including g-quasicontractions and mappings with a contractive iterate. In this way, several results obtained recently are generalized. Examples are provided when these results can be applied and neither corresponding metric results nor the results with the standard completeness assumption of the underlying partial metric space can. MSC:47H10, 54H25.
Existence of fixed point for GP(Λ;Θ)-contractive mappings in GP-metric spaces
2017
We combine some classes of functions with a notion of hybrid $GP_{(\Lambda,\Theta )}$ - $H$ - $F$ - contractive mapping for establishing some fixed point results in the setting of $GP$-metric spaces. An illustrative example supports the new theory.
Metal Complexes of Two Specific Regions of ZnuA, a Periplasmic Zinc(II) Transporter from Escherichia coli
2020
The crystal structure of ZnZnuA from Escherichia coli reveals two metal binding sites. (i) The primary binding site, His143, is located close the His-rich loop (residues 116-138) and plays a significant role in Zn(II) acquisition. (ii) The secondary binding site involves His224. In this work, we focus on understanding the interactions of two metal ions, Zn(II) and Cu(II), with two regions of ZnuA, which are possible anchoring sites for Zn(II): Ac-115MKSIHGDDDDHDHAEKSDEDHHHGDFNMHLW145-NH2 (primary metal binding site) and Ac-223GHFTVNPEIQPGAQRLHE240-NH2 (secondary metal binding site). The histidine-rich loop (residues 116-138) has a role in the capture of zinc(II), which is then further deliv…
No exception to the rule: Candidatus Portiera aleyrodidarum cell wall revisited
2014
International audience; Many insect endosymbionts described so far are gram-negative bacteria. Primary endosymbionts are obligatory bacteria usually harboured by insects inside vacuoles in specialized cells called bacteriocytes. This combination produces a typical three-membrane system with one membrane derived from the insect vacuole and the other two from the bacterial gram-negative cell envelope, composed by the cell wall (the outer membrane plus the periplasmic space) and the plasma membrane (the inner membrane). For the last 21 years, the primary endosymbiont of whiteflies 'Candidatus Portiera aleyrodidarum' was considered an exception to this rule. Previous works stated that only two …
Phylogenetic relationships among tetraploid species of Bellevalia (Asparagaceae) endemic to south-central Mediterranean
2017
AbstractIn the south-central Mediterranean four tetraploid species of Bellevalia occur: B. dolichophylla, B. galitensis, B. mauritanica, and B. pelagica. Another group of plants, morphologically similar to B. dolichophylla, has been recently recovered in Zembra Island (Tunisia). A phylogenetic reconstruction involving all these tetraploid taxa was performed using both plastidial and nuclear markers (trnL-trnF and ITS, respectively). For all these taxa, an allopolyploid origin involving B. romana and B. dubia is supported. Regarding plants from Zembra, they may fall within the variability of B. dolichophylla.
George-Veeramani Fuzzy Metrics Revised
2018
In this note, we present an alternative approach to the concept of a fuzzy metric, calling it a revised fuzzy metric. In contrast to the traditional approach to the theory of fuzzy metric spaces which is based on the use of a t-norm, we proceed from a t-conorm in the definition of a revised fuzzy metric. Here, we restrict our study to the case of fuzzy metrics as they are defined by George-Veeramani, however, similar revision can be done also for some other approaches to the concept of a fuzzy metric.
Best proximity point theorems for proximal cyclic contractions
2017
The purpose of this article is to compute a global minimizer of the function $$x\longrightarrow d(x, Tx)$$ , where T is a proximal cyclic contraction in the framework of a best proximally complete space, thereby ensuring the existence of an optimal approximate solution, called a best proximity point, to the equation $$Tx=x$$ when T is not necessarily a self-mapping.
Transmembrane signaling and cytoplasmic signal conversion by dimeric transmembrane helix 2 and a linker domain of the DcuS sensor kinase
2020
Transmembrane (TM) signaling is a key process of membrane-bound sensor kinases. The C4-dicarboxylate (fumarate) responsive sensor kinase DcuS of Escherichia coli is anchored by TM helices TM1 and TM2 in the membrane. Signal transmission across the membrane relies on the piston-type movement of the periplasmic part of TM2. To define the role of TM2 in TM signaling, we use oxidative Cys cross-linking to demonstrate that TM2 extends over the full distance of the membrane and forms a stable TM homodimer in both the inactive and fumarate-activated state of DcuS. An S186xxxGxxxG194 motif is required for the stability and function of the TM2 homodimer. The TM2 helix further extends on the periplas…
Characterization of the inner membrane protein BB0173 from Borrelia burgdorferi.
2017
Abstract Background The bacterial spirochete Borrelia burgdorferi is the causative agent of the most commonly reported arthropod-borne illness in the United States, Lyme disease. A family of proteins containing von Willebrand Factor A (VWFA) domains adjacent to a MoxR AAA+ ATPase have been found to be highly conserved in the genus Borrelia. Previously, a VWFA domain containing protein of B. burgdorferi, BB0172, was determined to be an outer membrane protein capable of binding integrin α3β1. In this study, the characterization of a new VWFA domain containing membrane protein, BB0173, is evaluated in order to define the location and topology of this multi-spanning membrane protein. In additio…