Moonlighting Proteins

Question 1

Was sind Moonlight Proteine (Schwarzarbeiter-Proteine)

Answer 1

Ein Protein, was mehrere Funktionen ausüben kann

A moonlighting protein is defined as a multifunctional protein in which two or more physiological, biochemical or biophysical functions are performed by a single polypeptide chain.

Question 2

Was ist beim Moonlight-Protein ausgeschlossen?

Answer 2

• splice variants (not a single polypeptide chain)
• proteolytic fragments (not a single polypeptide chain)
• families of homologous proteins (not a single polypeptide chain)
• gene fusions (no increase of biochemical functions)
• same reaction in different cellular locations (not two or more functions)

Question 3

Warum sollte man Moonlight Proteine nutzen?

Answer 3

 Energy saving
 No need to produce additional proteins
 Smaller genomes
 Easy fine-tuning
 Metabolic enzymes are the best sensors for their substrates
 Moonlighting proteins can connect metabolism and:
 signal transduction
 regulation of gene expression
 motility
 structural functions
 apoptosis

 Self regulation
 Many moonlighting proteins regulate their own transcription/translation
depending on the availability of their substrates

Question 3

Wer sind Typische Moonlight-Proteine?

Answer 3

 Highly conserved proteins
 Same moonlighting functions can be found in totally unrelated organisms
 Same proteins have different moonlighting functions in different organisms
 Highly abundant protein
 Genes encoding moonlighting proteins are expressed constitutively and at high levels
 Enzymes involved in central (carbon) metabolism
 10/10 enzymes of glycolysis possess moonlighting activity
 Typical candidates
 Metabolic enzymes
 Chaperons
 Membrane proteins (channels and receptors)

Question 4

Können Proteine an anderen Locations sein?

Answer 4

Ja, dort üben sie verschiedene Funktionen aus (wenn Moonlight)
z.B.: E.coli prolinedehydrogenase (PutA)
Membrane: proline utilization
Cytosol: transcription factor

Question 5

Wodurch können Proteine verschiedene Funktionen haben

Answer 5

• anderer Ort (z.B Membran und Cytosol)
• Co-Faktor Bindung

Question 6

Was sind die molekularen Mechanismen vom Moonlighting

Answer 6

1. verschiedene Locations (innerhalb und außerhalb der Zelle)
2. verschiedene Orte innerhalb einer Zelle bzw. Zellkompartimenten (Cytosol vs. Membran; Cytosol vs. nucleus)
3. Expression durch verschiedene Celltypen
4. Co-Faktor-Bindung
5. Oligomerizationsstatus
6. Komplexbildung
7. Mehrere Bindungstellen

Question 7

Was katalysiert GapDH

Answer 7

1. Es ist eine Schlüsselenzym in der Glycolyse und der Gluconeogenese (Zentral im Kohlenstoffstoffwechsel)
2. Substrat, welches zum Pentosephosphatweg gelinkt ist (Verbindung zum Nukleotidmetabolismus)

Question 8

Welche moonlight Funktionen wird hGapDH (human GapDH) zugeschrieben?

Answer 8

• Translokation von Proteinen
• Posttranskriptionale Generegulation
• Oxidative Stressantwort
• histone Generegulation
• Apoptose
• Schutz der teleomeren DNA
  …

Question 9

Welche moonlight Funktionen wird GapDH (bakterielles GapDH) zugeschrieben?

Answer 9

• DNA Reparatur
• RNA Degradierung
• Anheftung an Host-Zellen
• Eisenaufnahme
  …

Question 10

Wann kommt Virulenz der Bakterien vor?

Answer 10

Virulence occurs when bacteria have to fight for recourses with its host

Question 11

Was sind Trigger-Enzyme im Sinne der Moonlight Proteine?

Answer 11

Trigger enzymes are metabolic enzymes that additionally regulate gene expression
 Measurement of metabolites
 Control of gene expression depending on substrate availability

Question 12

Welche Art von Trigger-Enzyme gibt es?

Answer 12

• DNA bindend
• RNA bindend
• Protein Phosphorylierung
• Transkriptionsfaktor Bindung
• RNA Degradosom