Essential Genetics 6th Edition by Daniel Hartl

Exercise 20

Two E. coli genes, A and B , are known from mapping experiments to be very close to each other. A deletion mutation is isolated that eliminates the activity of both A and B. Neither the A nor the B protein can be found in the mutant, but a novel protein is isolated in which the amino-terminal 30 amino acids are identical to those of the B gene product and the carboxyl terminal 30 amino acids are identical to those of the A gene product.
(a) With regard to the 5' ?3' orientation of the nontranscribed DNA strand, is the order of the genes A B or B A ?
(b) Can you make any inference about the number of bases deleted?