Reivindicaciones

CLAIMS 1. An isolated nucleic acid sequence coding for a PntR transcription factor comprising a nucleotide sequence that is the same as, or is complementary to, or contains any suitable codon substitutions for any of those of SEQ ID NOs: 1, 3 or 5 or comprises a sequence which has at least 60% sequence homology with any of SEQ ID NOs: 1, 3 or 5. 2. An isolated nucleic acid sequence according to claim 1 which encodes a PntR transcription factor polypeptide comprising the amino acid sequence as shown in any of SEQ ID NOs: 2, 4 or 6 or a sequence having at least 75% identity thereto or an effective fragment thereof. 3. An isolated nucleic acid sequence according to claim 2 which is obtained from an Aspergillus, Trichoderma or Penicillium cell. 4. An isolated nucleic acid sequence according to claim 3 which is obtained from an Aspergillus* cell. 5. A plasmid or expression vector system comprising a nucleic acid sequence according to any of claims 1 to 4. 6. A host cell transformed or transfected with the plasmid or expression vector system of claim 5. 7. A polypeptide comprising the amino acid sequence corresponding to Aspergillus PntR or a functional equivalent thereof. 8. A polypeptide according to claim 7 having the same amino acid sequence or a sequence that is at least 75% identical to that of an Aspergillus PntR. 9. A polypeptide according to claim 7 or claim 8 comprising the amino acid sequence as shown in any of SEQ ID NOs: 2, 4 or 6 or a sequence having at least 75% identity thereto or an effective fragment thereof. 10. A nucleic acid construct arranged to knock down the expression or function of the transcription factor PntR. 11. A nucleic acid construct according to claim 10 comprising a nucleic acid sequence encoding a functionally disrupted PntR. 12. A nucleic acid construct according to claim 11 comprising a nucleic acid sequence encoding PntR and lacking the region encoding Zn2Cy6. 13. A nucleic acid construct according to claim 10 comprising all or a fragment of a nucleic acid sequence of any of claims 1 to 4. 14. A plasmid or vector system comprising a nucleic acid construct according to any of claims 10 to 13. 15. A method of disrupting PntR expression in a cell comprising introducing a nucleic acid construct as claimed in any of claims 10 to 13 or a plasmid or vector system as claimed in claim 14 into said cell. 16. A host cell transformed or transfected with a nucleic acid construct arranged to knock down the expression or function of the transcription factor PntR as claimed in any of claims 10 to 13 or a plasmid or vector system according to claim 14. 17. A host cell according to claim 16 further comprising a nucleic acid construct comprising a coding sequence of a protein of interest (POI) under the transcriptional control of a promoter regulated by XInR. 18. A host cell according to claim 16 or claim 17 wherein said host cell is selected from the group consisting of Aspergillus sp., Trichoderma and Penicillium sp. 19. A host cell according to any of claims 16 to 18 capable of producing an extracellular xylanase. 20. A host cell according to any of claims 16 to 19 wherein said cell is protease-deficient. 21. A host cell according to any of claims 16 to 20 wherein said cell has a block in L-arabinose metabolism. 22. A host cell according to any of claims 16 to 21 wherein said cell exhibits increased xylanase activity. 23. A host cell according to any of claims 16 to 22 wherein said cell is useful for production of a POI. 24. A method of expressing in a host cell a POI whose coding sequence is under the transcriptional control of a promoter regulated by XInR, said method comprising modulating the transcription factor PntR in said host cell. 25. A method according to claim 24 comprising the steps of providing a PntR-deficient host cell comprising the gene encoding the POI under XInR transcriptional control, and cultivating the host cell under suitable conditions. 26. A method according to any of claims 24 to 25 wherein the PntR has a nucleic acid sequence as set out in any of SEQ ID NOS: 1 , 3 or 5 or a sequence having more than 60% identity thereto. 27. A method according to any of claims 24 and 26 comprising using a host cell according to any of claims 16 to 23. 28. A method according to any of claims 24 to 27 wherein the POI is a homologous protein. 29. A method according to any of claims 24 to 27 wherein the POI is a heterologous protein. 30. A method according to any of claims 24 to 29 wherein the host cell is a filamentous fungal cell and, preferably, Aspergillus, Trichoderma or Penicillium spp. 31. A method according to any of claims 24 to 30 wherein said method of expressing a POI is part of a method of production of said POI and further comprisesisolating/purifying said POI. 32. A method of production of a POI comprising expressing in a host cell a POI whose coding sequence is under the transcriptional control of a promoter regulated by XInR, said method comprising modulating the transcription factor PntR in said host cell. 33. Use of modulation of the transcription factor PntR in the manufacture of a host cell to increase expression of a protein of interest (POI) whose coding sequence is under the transcriptional control of a promoter regulated by XInR.