Anchoring of Surface Proteins to the Cell Wall of Staphylococcus aureus. III. Lipid II is an in vivo peptidoglycan substrate for sortase-catalyzed surface protein anchoring

Surface proteins of Staphylococcus aureus are anchored to the cell wall peptidoglycan by a mechanism requiring a C-terminal sorting signal with an LPXTG motif. Surface proteins are first synthesized in the bacterial cytoplasm and then transported across the cytoplasmic membrane. Cleavage of the N-terminal signal peptide of the cytoplasmic surface protein P1 precursor generates the extracellular P2 species, which is the substrate for the cell wall anchoring reaction. Sortase, a membrane-anchored transpeptidase, cleaves P2 between the threonine (T) and the glycine (G) of the LPXTG motif and catalyzes the formation of an amide bond between the carboxyl group of threonine and the amino group of cell wall cross-bridges. We have used metabolic labeling of staphylococcal cultures with [32P]phosphoric acid to reveal a P3 intermediate. The 32P-label of immunoprecipitated surface protein is removed by treatment with lysostaphin, a glycyl-glycine endopeptidase that separates the cell wall anchor structure. Furthermore, the appearance of P3 is prevented in the absence of sortase or by the inhibition of cell wall synthesis. 32P-Labeled cell wall anchor species bind to nisin, an antibiotic that is known to form a complex with lipid II. Thus, it appears that the P3 intermediate represents surface protein linked to the lipid II peptidoglycan precursor. The data support a model whereby lipid II-linked polypeptides are incorporated into the growing peptidoglycan via the transpeptidation and transglycosylation reactions of cell wall synthesis, generating mature cell wall-linked surface protein

KAJIAN KEAMANAN PADA PROTECT DOCUMENT MICROSOFT OFFICE DENGAN MENGIMPLEMENTASIKAN ALGORITMA BRUTE FORCE DALAM MERETAS FILE DOCUMENT TERPROTEKSI

Banyak free software untuk meretas password pada protect document Microsoft office yang dapat diunduh dari internet. Dalam hal ini, bagaimana teknik atau metode yang digunakan oleh software tersebut dalam meretas password protect document Microsoft Office tersebut tidak dapat dikaji dengan pasti algoritma yang digunakannya. Pada penelitian sebelumnya penulis sudah pernah mengkaji dan mengimplemetasikan algoritma brute force untuk meretas password tidak disandikan, di mana dalam kajian ini algoritma brute force mampu meretas password yang digunakan walaupun kecepatan waktu proses retasi sangat berpengaruh terhadap panjang karakter, kombinasi karakter dan tipe karakter password yang digunakan. Pada pembahasan ini Algoritma brute force dicoba diterapkan dengan merancang sebuah aplikasi menggunakan bahasa pemrograman visual basic untuk meretas password yang digunakan pada protect document microsoft office word dan excel dan sekaligus mengkaji keamanan password yang digunakan, apakah disandikan atau tidak. Pada kajian ini, algoritma brute force berfungsi sebagai string maching antara file text yang tersembunyi yang dipanggil dengan fungsi “user32” dengan inisialisasi character password yang dijadikan sebagai pattern, dengan mecoba kemungkinan kemungkinan yang ada sesuai dengan panjang password, type karakter password dan kombinasi character password yang digunakan. Luaran dari kajian ini adalah aplikas

Industry 4.0 and sustainability: Towards conceptualization and theory

Both Industry 4.0 and sustainability have gained momentum in the academic, managerial and policy debate. Despite the relevance of the topics, the relation between Industry 4.0 and sustainability \u2013 revealed by many authors \u2013 is still unclear; literature is fragmented. This paper seeks to overcome this limit by developing a systematic literature review of 117 peer-reviewed journal articles. After descriptive and content analyses, the work presents a conceptualization and theoretical framework. The paper contributes to both theory and practice by advancing current understanding of Industry 4.0 and sustainability, especially the impact of Industry 4.0 technologies on sustainability practices and performance

Addressing a By-Product of the Opioid Addiction Crisis: Commercial Sexual Exploitation

In this webinar participants will learn what human trafficking and commercial sexual exploitation are. We will debunk some of the commonly held misconceptions and arm you with the true facts and statistics about prostitution. We will provide you with warning signs and red flags and help you to identify victims in need of support. We will explain the do’s and don’ts of working with victims and survivors of commercial sexual exploitation and equip participants with the tools and resources to assist this marginalized and vulnerable group of individuals

Structures of Sortase B from Staphylococcus aureus and Bacillus anthracis Reveal Catalytic Amino Acid Triad in the Active Site

Surface proteins attached by sortases to the cell wall envelope of bacterial pathogens play important roles during infection. Sorting and attachment of these proteins is directed by C-terminal signals. Sortase B of S. aureus recognizes a motif NPQTN, cleaves the polypeptide after the Thr residue, and attaches the protein to pentaglycine cross-bridges. Sortase B of B. anthracis is thought to recognize the NPKTG motif, and attaches surface proteins to m-diaminopimelic acid cross-bridges. We have determined crystal structure of sortase B from B. anthracis and S. aureus at 1.6 and 2.0 Å resolutions, respectively. These structures show a β-barrel fold with α-helical elements on its outside, a structure thus far exclusive to the sortase family. A putative active site located on the edge of the β-barrel is comprised of a Cys-His-Asp catalytic triad and presumably faces the bacterial cell surface. A putative binding site for the sorting signal is located nearby

A fluid-structure solver for confined microcapsule flows

We present a fluid-structure coupling method designed to study capsules flowing in a confined environment. The fluid solver is based on the Finite Volume Method and is coupled to a Finite Elements solid solver using the Immersed Boundary Method. We study the relaxation of a spherical capsule, initially deformed into an ellipsoid, and released in a square cross-section channel within a quiescent fluid environment. We perform a convergence study in order to validate the numerical method and consider the effect of the inertial forces on the capsule relaxation

Coordination of tolerogenic immune responses by the commensal microbiota

All mammals are born ignorant to the existence of micro-organisms. Soon after birth, however, every mammal begins a lifelong association with a multitude of microbes that lay residence on the skin, mouth, vaginal mucosa and gastrointestinal (GI) tract. Approximately 500–1000 different species of microbes have highly evolved to occupy these bodily niches, with the highest density and diversity occurring within the intestine [1]. These organisms play a vital role in mammalian nutrient breakdown and provide resistance to colonization by pathogenic micro-organisms. More recently, however, studies have demonstrated that the microbiota can have a profound and long-lasting effect on the development of our immune system both inside and outside the intestine [2]. While our immune system has evolved to recognize and eradicate foreign entities, it tolerates the symbiotic micro-organisms of the intestine. How and why this tolerance occurs has remained unclear. Here we present evidence that the commensal microbes of the intestine actively induce tolerant responses from the host that coordinate healthy immune responses. Potentially, disruption of this dialogue between the host and microbe can lead to the development of autoimmune diseases such as inflammatory bowel disease (IBD), rheumatoid arthritis (RA), or Type I diabetes (TID). As a wealth of publications have focused on the impact of the microbiota on intestinal immune responses and IBD, this chapter will focus on the extra-intestinal impacts of the microbiota from development to disease and integrate the known mechanisms by which the microbiota is able to actively communicate with its host to promote health

Finite Dimension Wyner-Ziv Lattice Coding for Two-Way Relay Channel

International audienceTwo-way relay channel (TWRC) models a cooperative communication situation performing duplex transmission via a relay station. For this channel, we have shown previously that a lattice-based physical layer network coding strategy achieves, at the limit of arbitrarily large dimension, the same rate as that offered by the random coding-based regular compress-and-forward. In this paper, we investigate a practical coding scheme using finite dimension lattices and offering a reasonable performance-complexity trade-off. The algorithm relies on lattice based quantization for Wyner-Ziv coding. We characterize the rate region allowed by our coding scheme, discuss the design criteria, and illustrate our results with some numerical examples