# 3. (a) Most antibiotics, or their precursors, are obtained from microorganisms that have been bred to...

###### Question:

3. (a) Most antibiotics, or their precursors, are obtained from microorganisms that have been bred to produce them in the best yields from simple nutrient precursors. Recently the field has been changed by successful efforts to clone the genes encoding the enzymes that mediate antibiotic biosynthesis. ( - HO =o HO HO For example, erythronolide 7, which is the precursor of erythromycin, is made by three proteins (DEBS1, DEBS2 and DEBS3), each of which is composed of several domains capable of catalysing a single step in the biosynthetic pathway. DH ER DEBS 1 DEBS 2 DEBS 3 Briefly explain the molecular features that allow the three proteins DEBS1, DEBS2 and DEBS3 to assemble in the correct order, and suggest a reason for why only DEBS1 has an N-terminal AT domain rather than a KS domain. (3 points)
(b) One method of obtaining novel variants of erythromycin is to introduce mutations into the PKS genes and thereby remove the enzyme activity associated with a given domain. By writing down the transformations catalysed by each domain of DEBS1 and DEBS2, select which of the following four novel erythromycin derivatives (8-11) would be obtained if the first enoylreductase domain (ER) in DEBS2 were rendered inactive by mutation. Curly-arrow mechanisms for each step are not required. (4 points) - HO HOU 3 НО HÓFOR НО HO L HO SU HOT НО HÓ HOS HO 8 9 10 11 (c) Briefly explain how erythromycin-producing bacteria (Streptomyces) avoid being killed by the antibiotic, and hence outline a potential problem associated with efforts to obtain novel erythromycin analogues by re-engineering the native gene cluster for erythromycin biosynthesis. (3 points)

#### Similar Solved Questions

##### Problem 10-18 Interest Rate RIS (LUS, CP44) 10 points Bond J has a coupon of 74...
Problem 10-18 Interest Rate RIS (LUS, CP44) 10 points Bond J has a coupon of 74 percent. Bond K has a coupon of 11.4 percent. Both bonds have 12 years to maturity and have a YTM of 78 percent. a. If interest rates suddenly rise by 2 percent, what is the percentage price change of these bonds? (A neg...
##### 18. C A nurse is caring for a 25 year old male patient who was infected...
18. C A nurse is caring for a 25 year old male patient who was infected with a disease that is attacking his central nervous system. The cause for the disease is due to an infection from a prion. This disease would be: A. Influenza A B. Salmonella typhi C.) Creutzfeldt-Jakob D. Neisseria gonorrhoeae...
##### 1. a. Find the main error in each of the band diagrams shown below. For all...
1. a. Find the main error in each of the band diagrams shown below. For all of the band diagrams Ny 1019/cm3, Ne- 1019/cm3, ni = 3 x 108/cm". E,-1.25 eV, T = 300 K. Ef Ef EFi Main error: Main error: Main error: Main error: Consider a semiconductor sample with the following characteristics: EG 1....
##### Need help with my final question 100 May 1- Sold merchandise costing to Mr Brogdon for...
Need help with my final question 100 May 1- Sold merchandise costing to Mr Brogdon for 120 cash invoice 157 May 4- Purchased merchandise for 3800 on. Credit from Hardaway Co. terms n 130 May 5. Purchased merchandise for 1300 on credit from CBJ Co. terms a wo. May le served sold merchandise costi...
##### The volume of Fort Peck Dam is 96,050 x 1,000m3
The volume of Fort Peck Dam is 96,050 x 1,000m3. Suppose the state of Montana decides to increase the volume of the dam. After the improvements, Fort Peck will hold 10 times as many cubic meters. How many cubic meters will Fort Peck hold after the improvements?...
##### A 100.0-tonne spacecraft moving in the +x-direction at 0.49 m/s docks with a 57.0-tonne spacecraft moving...
A 100.0-tonne spacecraft moving in the +x-direction at 0.49 m/s docks with a 57.0-tonne spacecraft moving in the -x-direction at 0.32 m/s. Find the velocity of the joined spacecraft....
##### 7.) Matt and Meg Comer are married. They do not have any children. Matt works as...
7.) Matt and Meg Comer are married. They do not have any children. Matt works as a history professor at a local university and earns a salary of $65,000. Meg works part-time at the same university. She earns$37,000 a year. The couple does not itemize deductions. Other than salary, the Comers’...
##### Exercise 9.7 Accounting for Trade-ins (LO9-5) Willis Bus Service traded in a used bus for a...
Exercise 9.7 Accounting for Trade-ins (LO9-5) Willis Bus Service traded in a used bus for a new one. The original cost of the old bus was $50,900. Accumulated depreciation at the time of the trade-in amounted to$35,400. The new bus cost $77,500 but Willis was given a trade-in allowance of$10,600. ...
##### Swifty C Raw materials inventory 75000 Work in process inventory 106000o Finished goods inventory100000 118000 92000...
Swifty C Raw materials inventory 75000 Work in process inventory 106000o Finished goods inventory100000 118000 92000 $1454000 O$144...
##### We were unable to transcribe this imageName of teenage drivers has a reaction time between 0.45...
We were unable to transcribe this imageName of teenage drivers has a reaction time between 0.45 and 0.70 seconds? d) What is the percentile rank for a teenage driver who has a reaction time of 50 seconds?...
Chapter 11 - Homework eBook Calculator Print Item Average Rate of Return-Cost Savings Midwest Fabricators Inc. is considering an investment in equipment that will replace direct labor. The equipment has a cost of $101,000 with a$9,000 residual value and a five-year life. The equipment will replace ...