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OBPgp279

OBPgp279 is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand OBPgp279 rather than just read about it. In short: OBPgp279 (OBP genome protein 279) is an endolysin that hydrolyzes peptidoglycan, a major constituent in bacterial membrane. OBPgp279 is found in Pseudomonas fluorescens phage OBP, which belongs in the Myoviridae family of bacteriophages.

OBPgp279 — main illustration
OBPgp279 — illustration

Key takeaways

  • OBPgp279 belongs to science; place it in that map before memorising details.
  • Learn the definition first, then one example that makes the definition concrete.
  • Connect OBPgp279 to a quantity you can measure, compute or draw — that is where exam questions come from.
  • Reproduce the core statement of OBPgp279 from memory before moving on to harder problems.

Reference excerpt

OBPgp279 (OBP genome protein 279) is an endolysin that hydrolyzes peptidoglycan, a major constituent in bacterial membrane. OBPgp279 is found in Pseudomonas fluorescens phage OBP, which belongs in the Myoviridae family of bacteriophages. Because of its role in hydrolyzing the peptidoglycan layer, OBPgp279 is a key enzyme in the lytic cycle of the OBP bacteriophage; it allows the bacteriophage to lyse its host internally to escape. Unlike other endolysins, OBPgp279 does not rely on holins to perforate the inner bacterial membrane in order to reach the peptidoglycan layer. Although OBPgp279 is not a well-studied enzyme, it has garnered interest as a potential antibacterial protein due to its activity against multidrug-resistant gram-negative bacteria.

Predicted enzyme mechanism

The mechanism of OBPgp279 is predicted to be part of glycoside hydrolase family 19 (GH19) due to the presence of a conserved sequence motif (general sequence motif=[FHY]-G-R-G-[AP]-ζ-Q-[IL]-[ST]-[FHYW]-[HN]-[FY]-[NY], ζ= hydrophilic amino acid) in the catalytic domain of the enzyme. GH19 is a group of endo-acting enzymes that hydrolyzes the glycosidic bonds of β-1,4-linked N-Acetylglucosamine (GlcNAc) typically within chitin; however, some enzymes in this family also demonstrate lysozyme activity. Since bacterial cell walls do not contain chitin, OBPgp279 hydrolyzes β-1,4-linked GlcNAc in peptidoglycan. The hydrolysis of β-1,4-linked GlcNAc is catalyzed by two glutamate residues in the active side, one acting as a general acid, and another acting as a general base. There is limited detail on the catalytic mechanism of OBPgp279. However, because OBPgp279 is part of GH19, it is possible to infer the structure of OBPgp279 binding to peptidoglycan from the substrate binding of glycoside hydrolase family 19. The figure on the right shows an example of a glycoside hydrolase family 19 binding to chitin. OBPgp279 most likely has a similar active site, but it binds to peptidoglycan instead of chitin. Due to the activity of OBPgp279 on β-1,4-linked GlcNAc, it is likely that OBPgp279 is a N-acetylmuramidase (lysozyme-like) endolysin which hydrolyzes the sugar backbone component of the peptidoglycan on the reducing side of GlcNAc.

Enzyme domain organization The catalytic domain of the enzyme resides on the C-terminal region of the enzyme. OBPgp279 is also predicted to contain peptidoglycan binding domains; since OBPgp279 contains two peptidoglycan binding domain motifs in its N-terminal region (general sequence motif=D-G-(Pho)2-G-K/N-G/N-T, Pho =  hydrophobic amino acid), it likely contains two peptidoglycan binding domains as shown in the schematic drawing below.

Application OBPgp279 has gained attention as a potential antibiotic because of the increasing prevalence of multidrug resistant gram-negative bacteria. Typically, most endolysins rely on holin to reach the peptidoglycan layer of gram-negative bacteria. This limits their efficacy as standalone antibiotics; without holins or any membrane permeabilizers, they have low membrane penetration. In contrast, OBPgp279 is capable of penetrating the bacterial outer membrane to reach the peptidoglycan layer without needing holins or any membrane permeabilizers. In addition, unlike most endolysins, OBPgp279 demonstrates high efficacy against a variety of bacteria instead of being species-specific. Compared to small molecule antibiotics, OBPgp279 also has the advantages of a low chance of bacterial resistance, specificity towards pathogen-causing bacteria, and efficacy on mucosal surfaces. In 2013, Katholieke Universiteit Leuven (KU Leuven) professor Rob Lavigne modified OBPgp279 by adding a polycationic nonapeptide to its C-terminus, thereby improving its efficacy as an antibiotic. The addition of the polycationic nonapeptide improved OBPgp279's log reduction against various gram-negative and gram-positive bacteria by as much as three logs. This improvement is likely because of increased outer membrane penetration, in turn caused by favorable electrostatic interaction between the cationic nonapeptide and the negatively charged bacterial membrane. The engineered OBPgp279, along with the engineering technology platform, is currently owned by Boehringer Ingelheim Vetmedica. The major drawback of working with OBPgp279 and other endolysins is their immunogenicity. Although studies show that antibodies do not affect the efficacy of endolysins in animal models, immunogenicity must be monitored if OBPgp279 is pursued for medical use.

References

Illustrations

OBPgp279 illustration
OBPgp279: Active site of gycoside hydrolase family 19 papaya chitinase (PDB: 3cql​).[4] Conserved residues are shown surrounding the catalytic acid, Glu67. A GlcNAc2 unit binding in the -1 and +1 subsites is shown in narrow stick representation and an arrow indicates the position of the glycosidic oxygen.
Active site of gycoside hydrolase family 19 papaya chitinase (PDB: 3cql​).[4] Conserved residues are shown surrounding the catalytic acid, Glu67. A GlcNAc2 unit binding in the -1 and +1 subsites is shown in narrow stick representation and an arrow indicates the position of the glycosidic oxygen.
OBPgp279: The domain organization of OBPgp279.[1] The E-values for OBP domains predicted by HHpred are shown below the respective domains.
The domain organization of OBPgp279.[1] The E-values for OBP domains predicted by HHpred are shown below the respective domains.

Worked examples

Example 1 — a first encounter with OBPgp279

Start with the simplest possible case. Write down what OBPgp279 claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to OBPgp279 before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about OBPgp279 ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of OBPgp279

In research
OBPgp279 appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry
Engineering practice reuses OBPgp279 in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom
OBPgp279 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Bacteriophages, EC 3.2.1, Viral enzymes, so understanding it makes those chapters shorter.
In everyday life
Look for OBPgp279 outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study OBPgp279 in 20 minutes

  1. Read the reference excerpt below once, without taking notes.
  2. Close the page and write down what OBPgp279 means in your own words.
  3. Compare your version with the excerpt and mark what you missed.
  4. Work through the three examples above with pen and paper.
  5. Explain OBPgp279 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is OBPgp279 in simple terms?

OBPgp279 (OBP genome protein 279) is an endolysin that hydrolyzes peptidoglycan, a major constituent in bacterial membrane. OBPgp279 is found in Pseudomonas fluorescens phage OBP, which belongs in the Myoviridae family of bacteriophages.

Why does OBPgp279 matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study OBPgp279?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on OBPgp279.

Tags

  • Bacteriophages
  • EC 3.2.1
  • Viral enzymes

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