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Integration specificities of two lambdoid phages (21 and e14) that insert at the same attB site.

ABSTRACT: It was shown previously that phage 21 and the defective element e14 integrate at the same site within the icd gene of Escherichia coli K-12 but that 21 integrase and excisionase excise e14 in vivo very infrequently compared to excision of 21. We show here that the reverse is also true: e14 excises itself much better than it excises an adjacent 21 prophage. In vitro integrase assays with various attP substrates delimit the minimal attP site as somewhere between 366 and 418 bp, where the outer limits would include the outermost repeated dodecamers suggested as arm recognition sites by S. J. Schneider (Ph.D. dissertation, Stanford University, Stanford, Calif., 1992). We speculate that the reason 21 attP is larger than lambda attP (240 bp) is because it must include a 209-bp sequence homologous to the 3' end of the icd transcript in order to allow icd expression in lysogens. Alteration of portions of 21 attP to their e14 counterparts shows that 21 requires both the arm site and core site sequences of 21 but that replacements by e14 sequences function in some positions. Consistent with Schneider's in vivo results, and like all other known integrases from lambdoid phages, 21 requires integration host factor for activity.

SUBMITTER: Wang H

PROVIDER: S-EPMC179457 | biostudies-other | 1997 Sep

REPOSITORIES: biostudies-other

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Integration specificities of two lambdoid phages (21 and e14) that insert at the same attB site.

Wang H H Yang C H CH Lee G G Chang F F Wilson H H del Campillo-Campbell A A Campbell A A

Journal of bacteriology 19970901 18

It was shown previously that phage 21 and the defective element e14 integrate at the same site within the icd gene of Escherichia coli K-12 but that 21 integrase and excisionase excise e14 in vivo very infrequently compared to excision of 21. We show here that the reverse is also true: e14 excises itself much better than it excises an adjacent 21 prophage. In vitro integrase assays with various attP substrates delimit the minimal attP site as somewhere between 366 and 418 bp, where the outer lim ...[more]

PMID: 9294425

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Project description:Congenital adrenal hyperplasia (CAH) is one of the most frequent autosomal recessive diseases in Europe. Treatment is a challenge for pediatric endocrinologists. Important parameters to judge the outcome are adult height and menstrual cycle. We report the follow-up from birth to adulthood of two Caucasian sisters with salt-wasting CAH due to the same mutation, homozygosity c.290-13A>G (I2 splice), in the 21-hydroxylase gene. Their adherence to treatment was excellent. Our objective was to distinguish the effects of treatment with hydrocortisone (HC) and fludrocortisone (FC) on final height (FH) from constitutional factors. The older girl (patient 1), who showed virilized genitalia Prader scale III-IV at birth, reached FH within familial target height at 18 years of age. Menarche occurred at the age of 15. Her menstrual cycles were always irregular. Total pubertal growth was normal (29 cm). She showed a growth pattern consistent with constitutional delay. The younger sister (patient 2) was born without masculinization of the genitalia after her mother was treated with dexamethasone starting in the fourth week of pregnancy. She reached FH at 16 years of age. Her adult height is slightly below familial target height. Menarche occurred at the age of 12.5, followed by regular menses. Total pubertal growth was normal (21 cm). The average dose of HC from birth to FH was 16.7 mg/m2 in patient 1 and 16.8 mg/m2 in patient 2. They received FC once a day in doses from 0.05 to 0.1 mg. Under such therapy, growth velocity was normal starting from the age of 2.5 years with an overall average of +0.2 SD in patient 1 and -0.1 SD in patient 2, androstenedione levels were always within normal age range. Similarly, BMI and blood pressure were always normal, no acne and no hirsutism ever appeared. In conclusion, two siblings with the same genetic form of 21-hydroxylase deficiency and excellent adherence to medication showed different growth and menstrual cycle patterns, rather related to constitutional factors than to underlying CAH. In addition, the second patient represents an example of successful in utero glucocorticoid treatment to prevent virilization of the external genitalia.

Dataset Information

Integration specificities of two lambdoid phages (21 and e14) that insert at the same attB site.

Publications

Integration specificities of two lambdoid phages (21 and e14) that insert at the same attB site.

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