Maltose utilization in E. coli requires the proteins encoded by genes in three d

Question

Maltose utilization in E. coli requires the proteins encoded by genes in three different operons. One operon includes the genes malE, malF, and malG; the second includes malK and lamB; and the genes in the third operon are malP and malQ. The MalT protein is a positive regulator that regulates the expression of all three operons.

A) What phenotype would you expect to result from a loss-of-function mutation in the malT gene?

In order to infect E. coli, bacteriophage ? binds to the maltose transport protein LamB (also known as the ? receptor protein) that is found in the outer membrane of the bacterial cell. The synthesis of LamB is induced by maltose in the medium via expression of the MalT protein, as described above.

B) List the culture conditions under which wild-type E. coli cells would be sensitive to infection by bacteriophage ?.

C) E. coli cells that are resistant to infection by bacteriophage ? have been isolated. List the types of mutations in the maltose regulon that ?-resistant mutants could contain.

Explanation / Answer

loss of function mutation in malT gene will not allow thee expression of any operons----- so E.coli will not be ble to utilise maltose from the medium , will be deprived of energy.

culture conditions: if there is mltose present in the medium , sp LamB will be induced , bacteriophage will be able to infect E.coli.

mutation in the MalT gene , will create resistance , which will render MalT gene non functional , so LamB will not be expressed , and bacteriophage will not be able to infect E.coli.

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